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Sample records for south central alaska

  1. South Central Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Glacial silt along the Copper River in Alaska is picked up by the wind and carried out over the Gulf of Alaska. This true-color MODIS image from October 26, 2001, shows a large gray dust plume spreading out over the Gulf. West of the Copper River Delta, Cook Inlet is full of sediment.

  2. GIS coverages of the Castle Mountain Fault, south central Alaska

    USGS Publications Warehouse

    Labay, Keith A.; Haeussler, Peter J.

    2001-01-01

    The Castle Mountain fault is one of several major east-northeast-striking faults in southern Alaska, and it is the only fault with had historic seismicity and Holocene surface faulting. This report is a digital compilation of three maps along the Castle Mountain fault in south central Alaska. This compilation consists only of GIS coverages of the location of the fault, line attributes indicating the certainty of the fault location, and information about scarp height, where measured. The files are presented in ARC/INFO export file format and include metadata.

  3. Index of streamflow and water quality records to September 30, 1978, south-central Alaska

    USGS Publications Warehouse

    Still, Patsy J.

    1980-01-01

    This report, which is one of a series of reports for Alaska, lists stations in south-central Alaska at which streamflow and water quality data have been collected by the U.S. Geological Survey. Included are a hydrologic subregion map of south-central Alaska and a table listing the types of data collected and periods of record. (USGS)

  4. Emsian (late Early Devonian) sponges from west-central and south-central Alaska

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Anderson, N.K.

    2009-01-01

    Relatively common specimens of the hypercalcified agelasiid sponge Hormospongia labyrinthica Rigby and Blodgett, 1983 and specimens of associated species of Hormospongia have been previously reported from Emsian and Eifelian stratigraphic units at several localities in south-central and southeastern Alaska (Rigby and Blodgett, 1983). Those sponges were first described from the type section of the Eifelian Cheeneetnuk Limestone in the McGrath A-5 quadrangle. Since then several additional specimens of Hormospongia labyrinthica have also been collected from a new locality in the Talkeetna C-6 quadrangle in southcentral Alaska (Figs. 1, 2.1), and are documented here.

  5. Geologic framework and petroleum systems of Cook Inlet basin, south-central Alaska

    USGS Publications Warehouse

    LePain, D.L.; Stanley, R.G.; Helmold, K.P.; Shellenbaum, D.P.

    2013-01-01

    This report provides a comprehensive overview of the stratigraphy, structure, tectonics, and petroleum systems of the Cook Inlet basin, an important oil- and gas-producing region in south-central Alaska.

  6. Seismicity and plate tectonics in south central Alaska

    NASA Technical Reports Server (NTRS)

    Van Wormer, J. D.; Davies, J.; Gedney, L.

    1974-01-01

    Hypocenter distribution shows that the Benioff zone associated with the Aleutian arc terminates in interior Alaska some 75 km north of the Denali fault. There appears to be a break in the subducting Pacific plate in the Yentna River-Prince William Sound area which separates two seismically independent blocks, similar to the segmented structure reported for the central Aleutian arc.

  7. 40 CFR 81.247 - South Central Alaska Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false South Central Alaska Intrastate Air Quality Control Region. 81.247 Section 81.247 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... portions of the 1956 Election Districts 7-17, inclusive, and Election District 24 as described in...

  8. Tephrochronologic Dating and Correlation of Historic and Prehistoric Tsunami Deposits in South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Beget, J. E.; Combellick, R. A.; Addison, J.

    2007-12-01

    Volcanic Ash deposits can be used to identify, date and correlate tsunami deposits in the Cook Inlet and Prince William Sound areas of south-central Alaska. The 1964 Good Friday Earthquake (M9.2) produced a major regional tsunami that affected the entire coast of south-central Alaska, and coeval submarine landslides in Prince William Sound generated local tsunamis more than 30 m high. The 1964 tsunami deposits on Augustine Island in Cook Inlet are partly buried by tephras and pyroclastic flows from recent eruptions and record an 8-m-high wave. Tsunami deposits recording a volcanic tsunami produced by an eruption at Augustine Volcano in 1883 indicate initial wave heights of more than 18 m, and are overlain by coeval 1883 tephra and also Katmai 1912 tephra at multiple sites on Augustine Island, as well as at Nanwalek and Homer 80-100 km to the north. Newly discovered tsunami deposits recording the penultimate great earthquake on the subduction zone beneath south- central Alaska are dated to ca. 950 yr BP near Valdez. The tsunami deposits are overlain by a mafic tephra from the Wrangell area erupted ca. 750 yr BP. The tephra and new dates on the tsunami deposit help refine the age of the late major earthquake on the subduction zone beneath south-central Alaska, as there is wide range of radiocarbon dates associated with broadly coeval episodes of local subsidence identified at sites in Prince William Sound and Cook Inlet. A regionally extensive Augustine tephra erupted ca. 800 yr BP occurs in sediments deposited after the subsidence at several sites around Cook Inlet, and further helps refine the age of the penultimate great earthquake in south-central Alaska. An older tsunami deposit located near Homer is dated to ca. 3400 yr BP and occurs above tephra from Redoubt Volcano, and records an older subduction zone earthquake. A still older tsunami deposit dated to 3600 yr BP directly underlies the Redoubt tephra, and may have been generated by a huge eruption at Redoubt

  9. A slow slip event in the south central Alaska Subduction Zone and related seismicity anomaly

    NASA Astrophysics Data System (ADS)

    Wei, Meng; McGuire, Jeffrey J.; Richardson, Eliza

    2012-08-01

    We detected a slow slip event in the south central Alaska Subduction Zone by analyzing continuous GPS data from the Plate Boundary Observatory (PBO) network. The slow slip event started in early 2010 at a depth of 35 km beneath the Cook Inlet, near the down-dip end of the locked zone, and is ongoing as of November 2011 with an accumulated magnitude of Mw 6.9. Analysis of the earthquake catalog in the same area using the stochastic Epidemic Type Aftershock Sequence model (ETAS) shows a small but detectable seismicity increase during the slow slip event. We also find a change in seismicity rate around 1998, that may suggest an earlier slow slip event in the same region. Slow slip events in Alaska appear more widespread than previously thought but have remained undetected due to their long durations, the time intervals between them, and the limited time records from the continuous GPS.

  10. Geologic map of the Gulkana B-1 quadrangle, south-central Alaska

    SciTech Connect

    Richter, D.H.; Ratte, J.C.; Schmoll, H.R.; Leeman, W.P.; Smith, J.G.; Yehle, L.A.

    1989-01-01

    The quadrangle includes the Capital Mountain Volcano and the northern part of Mount Sanford Volcano in the Wrangell Mountains of south-central Alaska. The Capital Mountain volcano is a relatively small, andesitic shield volcano of Pleistocene age, which contains a 4-km-diameter summit caldera and a spectacular post-caldera radial dike swam. Lava flows from the younger Pleistocene Mount Sanford Volcano overlap the south side of the Capital Mountain Volcano. Copper-stained fractures in basaltic andesite related to a dike-filled rift of the North Sanford eruptive center are the only sign of mineralization in the quadrangle. Rock glaciers, deposits of Holocene and Pleistocene valley glaciers and Pleistocene Copper River basin glaciers mantle much of the volcanic bedrock below elevations of 5,500 ft.

  11. Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska.

    PubMed

    Sherriff, Rosemary L; Berg, Edward E; Miller, Amy E

    2011-07-01

    We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Niño years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Niño-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years. PMID:21870620

  12. A Century of Retreat at Portage Glacier, South-Central Alaska

    USGS Publications Warehouse

    Kennedy, Ben W.; Trabant, Dennis C.; Mayo, Lawrence R.

    2006-01-01

    Introduction: The Portage Glacier, in south-central Alaska, is viewed by thousands of visitors annually who come to the U.S. Forest Service Begich, Boggs Visitor Center located on the road system between Anchorage and Whittier, Alaska. During the past century, the terminus of the glacier has retreated nearly 5 kilometers to its present location (fig. 1). Like other glaciers that terminate in water, such as Columbia Glacier near Valdez or Mendenhall Glacier near Juneau, Portage Glacier has experienced accelerated retreats in recent decades that likely were initially triggered by climate change begun at the end of the Little Ice Age in the mid-1800s and subsequently controlled in recent history primarily by calving of the glacier terminus. Photographic records of the terminus covering 1914 until present day track the patterns of retreat. These data, coupled with USGS climate information collected from the southern end of the ice field, provide insight to the patterns of retreat that might be observed in the future.

  13. Measurement and Modeling of Cryosphere-Geosphere Interactions in South Central Alaska

    NASA Astrophysics Data System (ADS)

    Sauber, J. M.; Han, S. C.; Luthcke, S. B.; Ruppert, N. A.; Bruhn, R. L.

    2014-12-01

    In south central Alaska large cryosphere fluctuations occur on a variety of temporal and spatial scales in a region of upper crustal faulting and folding associated with collision and accretion of the Yakutat terrane. Over the last decade (2002-present) the Gravity Recovery and Climate Experiment (GRACE) gravity measurements from southern Alaska indicate region-specific trends of annual mass loss and large variable seasonal mass fluctuations. Unraveling the various geophysical signals within GRACE and continuous GPS data, as well as earlier campaign GPS data, has required acquiring geodetic constraints on changes in the cryosphere from satellite, aircraft, and in situ data. At broad spatial scales, short-term atmospheric loading corrections are important as well. On a more local scale, we use snow accumulation profiles from Larson's GPS reflectometry, SNOTEL sites, and MODIS derived melt onset/refreeze timing to estimate the magnitude and timing of seasonal cryosphere loading and unloading. The regional GRACE trends need to be corrected for the rheological response to century time-scale ice mass loss as well. Our numerical modeling of the solid Earth response to cryosphere changes and earthquakes includes use of simple elastic models, regional finite element modeling with PyLith and a global normal model approach. For instance, our calculations predict the region specific GRACE trends due to ongoing mass change associated with viscoelastic relaxation following the 1964 and other earthquakes.

  14. Stratigraphic and compositional complexities of the late Quaternary Lethe tephra in South-central Alaska

    USGS Publications Warehouse

    Riehle, J.R.; Ager, T.A.; Reger, R.D.; Pinney, D.S.; Kaufman, D.S.

    2008-01-01

    Recently discovered Lethe tephra has been proposed as a latest Pleistocene marker bed in Bristol Bay lowland NE to the Cook Inlet region, Alaska, on the basis of correlations involving a single "Lethe average" glass composition. Type deposits in the Valley of Ten Thousand Smokes, however, are chemically heterogeneous-individual lapilli as well as aggregate ash deposits have glass compositions that range from the average mode to much higher SiO2 and K2O. Moreover, a lake-sediment core from the Cook Inlet region contains one ash deposit similar to "Lethe average" and other, closely underlying deposits that resemble a mixture of the average mode and high-Si high-K mode of proximal deposits. Synthesis of previously published radiocarbon ages indicates a major eruption mainly of "Lethe average" mode about 13,000 14C yr BP. As many as six deposits in the Cook Inlet region-five chiefly "Lethe average" mode-range from about 13,000 to 15-16,000 14C yr BP, and an early Holocene deposit in the Bristol Bay lowland extends the minimum age range of Lethe tephra throughout this region to 8000 14C yr BP. Because of the appearance of "Lethe average" composition in multiple deposits spanning thousands of years, we urge caution when using a Lethe-like composition as a basis for inferring a latest Pleistocene age of a tephra deposit in south-central Alaska. Linear variation plots suggest that magma mixing caused the Lethe heterogeneity; multiple magmas were involved as well in other large pyroclastic eruptions such as Katmai (Alaska) and Rotorua (New Zealand). Lethe is an example of a heterogeneous tephra that may be better compared with other tephras by use of plots of individual analytical points rather than by calculating similarity coefficients based on edited data. ?? 2006 Elsevier Ltd and INQUA.

  15. Three-dimensional numerical models of flat slab subduction and the Denali fault driving deformation in south-central Alaska

    NASA Astrophysics Data System (ADS)

    Jadamec, Margarete A.; Billen, Magali I.; Roeske, Sarah M.

    2013-08-01

    Early theories of plate tectonics assumed plates were rigid with deformation limited to within a few tens of kilometers of the plate boundary. However, observations indicate most continental plates defy such rigid behavior with deformation extending over 1000 kilometers inboard. We construct three-dimensional (3D) numerical models of the boundary between the Pacific and North American plates in Alaska to investigate the relative controls of flat slab subduction, continental scale faulting, and a non-linear rheology on deformation in the overriding plate. The models incorporate a realistic slab shape based on seismicity and seismic tomography and a variable thermal structure for both the subducting and overriding plates based on geologic and geophysical observables. The inclusion of the Denali fault in the models allows for the portion of south-central Alaska between the Denali fault and the trench to partially decouple from the rest of North America, forming an independently moving region that correlates to what has been described from geologic and geodetic studies as the Wrangell block. The motion of the Wrangell block tracks the motion of the flat slab in the subsurface indicating the subducting plate is driving the motion of the Wrangell block. Models using a composite (Newtonian and non-Newtonian) viscosity predict compressional motion along the northern bend in the Denali fault, consistent with thermochronologic data that show significant late Neogene exhumation in the central Alaska Range, including at Mt. McKinley, the tallest mountain in North America. These 3D numerical models of the Pacific-North American margin in Alaska show the subducting slab is the main driver of overriding plate deformation in south-central Alaska and combined with the Denali fault can reproduce several first order tectonic features of the region including the motion of the Wrangell block, uplift in the central Alaska Range, subsidence in the Cook Inlet-Susitna Basins, and upwelling

  16. Shrubline but not treeline advance matches climate velocity in montane ecosystems of south-central Alaska.

    PubMed

    Dial, Roman J; Scott Smeltz, T; Sullivan, Patrick F; Rinas, Christina L; Timm, Katriina; Geck, Jason E; Carl Tobin, S; Golden, Trevor S; Berg, Edward C

    2016-05-01

    Tall shrubs and trees are advancing into many tundra and wetland ecosystems but at a rate that often falls short of that predicted due to climate change. For forest, tall shrub, and tundra ecosystems in two pristine mountain ranges of Alaska, we apply a Bayesian, error-propagated calculation of expected elevational rise (climate velocity), observed rise (biotic velocity), and their difference (biotic inertia). We show a sensitive dependence of climate velocity on lapse rate and derive biotic velocity as a rigid elevational shift. Ecosystem presence identified from recent and historic orthophotos ~50 years apart was regressed on elevation. Biotic velocity was estimated as the difference between critical point elevations of recent and historic logistic fits divided by time between imagery. For both mountain ranges, the 95% highest posterior density of climate velocity enclosed the posterior distributions of all biotic velocities. In the Kenai Mountains, mean tall shrub and climate velocities were both 2.8 m y(-1) . In the better sampled Chugach Mountains, mean tundra retreat was 1.2 m y(-1) and climate velocity 1.3 m y(-1) . In each mountain range, the posterior mode of tall woody vegetation velocity (the complement of tundra) matched climate velocity better than either forest or tall shrub alone, suggesting competitive compensation can be important. Forest velocity was consistently low at 0.1-1.1 m y(-1) , indicating treeline is advancing slowly. We hypothesize that the high biotic inertia of forest ecosystems in south-central Alaska may be due to competition with tall shrubs and/or more complex climate controls on the elevational limits of trees than tall shrubs. Among tall shrubs, those that disperse farthest had lowest inertia. Finally, the rapid upward advance of woody vegetation may be contributing to regional declines in Dall's sheep (Ovis dalli), a poorly dispersing alpine specialist herbivore with substantial biotic inertia due to dispersal

  17. Assessment of unconvential (tight) gas resources in Upper Cook Inlet Basin, South-central Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Nelson, Philip H.; Klett, Timothy R.; Le, Phuong A.; Anderson, Christopher P.

    2015-01-01

    A geologic model was developed for the assessment of potential Mesozoic tight-gas resources in the deep, central part of upper Cook Inlet Basin, south-central Alaska. The basic premise of the geologic model is that organic-bearing marine shales of the Middle Jurassic Tuxedni Group achieved adequate thermal maturity for oil and gas generation in the central part of the basin largely due to several kilometers of Paleogene and Neogene burial. In this model, hydrocarbons generated in Tuxedni source rocks resulted in overpressure, causing fracturing and local migration of oil and possibly gas into low-permeability sandstone and siltstone reservoirs in the Jurassic Tuxedni Group and Chinitna and Naknek Formations. Oil that was generated either remained in the source rock and subsequently was cracked to gas which then migrated into low-permeability reservoirs, or oil initially migrated into adjacent low-permeability reservoirs, where it subsequently cracked to gas as adequate thermal maturation was reached in the central part of the basin. Geologic uncertainty exists on the (1) presence of adequate marine source rocks, (2) degree and timing of thermal maturation, generation, and expulsion, (3) migration of hydrocarbons into low-permeability reservoirs, and (4) preservation of this petroleum system. Given these uncertainties and using known U.S. tight gas reservoirs as geologic and production analogs, a mean volume of 0.64 trillion cubic feet of gas was assessed in the basin-center tight-gas system that is postulated to exist in Mesozoic rocks of the upper Cook Inlet Basin. This assessment of Mesozoic basin-center tight gas does not include potential gas accumulations in Cenozoic low-permeability reservoirs.

  18. Assessment of undiscovered oil and gas resources of the Cook Inlet region, south-central Alaska, 2011

    USGS Publications Warehouse

    Stanley, Richard G.; Charpentier, Ronald R.; Cook, Troy A.; Houseknecht, David W.; Klett, Timothy R.; Lewis, Kristen A.; Lillis, Paul G.; Nelson, Philip H.; Phillips, Jeffrey D.; Pollastro, Richard M.; Potter, Christopher J.; Rouse, William A.; Saltus, Richard W.; Schenk, Christopher J.; Shah, Anjana K.; Valin, Zenon C.

    2011-01-01

    The U.S. Geological Survey (USGS) recently completed a new assessment of undiscovered, technically recoverable oil and gas resources in the Cook Inlet region of south-central Alaska. Using a geology-based assessment methodology, the USGS estimates that mean undiscovered volumes of nearly 600 million barrels of oil, about 19 trillion cubic feet of natural gas, and 46 million barrels of natural gas liquids remain to be found in this area.

  19. Coalbed methane, Cook Inlet, south-central Alaska: A potential giant gas resource

    USGS Publications Warehouse

    Montgomery, S.L.; Barker, C.E.

    2003-01-01

    Cook Inlet Basin of south-central Alaska is a forearc basin containing voluminous Tertiary coal deposits with sufficient methane content to suggest a major coalbed gas resource. Coals ranging in thickness from 2 to 50 ft (0.6 to 15 m) and in gas content from 50 to 250 scf/ton (1.6 to 7.8 cm2/g) occur in Miocene-Oligocene fluvial deposits of the Kenai Group. These coals have been identified as the probable source of more than 8 tcf gas that has been produced from conventional sandstone reservoirs in the basin. Cook Inlet coals can be divided into two main groups: (1) those of bituminous rank in the Tyonek Formation that contain mainly thermogenic methane and are confined to the northeastern part of the basin (Matanuska Valley) and to deep levels elsewhere; and (2) subbituminous coals at shallow depths (<5000 ft [1524 m]) in the Tyonek and overlying Beluga formations, which contain mainly biogenic methane and cover most of the central and southern basin. Based on core and corrected cuttings-desorption analyses, gas contents average 230 scf/ton (7.2 cm2/g) for bituminous coals and 80 scf/ton (2.5 cm2/g) for subbituminous coals. Isotherms constructed for samples of both coal ranks suggest that bituminous coals are saturated with respect to methane, whereas subbituminous coals at shallow depths along the eroded west-central basin margin are locally unsaturated. A preliminary estimate of 140 tcf gas in place is derived for the basin.

  20. Breeding ecology of Wandering Tattlers Tringa incana: a study from south-central Alaska

    USGS Publications Warehouse

    Gill, Robert; Tomkovich, Pavel S.; Dementyev, Maksim N.

    2015-01-01

    Montane-nesting shorebirds are arguably the least studied of the Charadriiformes, owing in part to the remoteness of their breeding areas, low nesting densities, and specialized behaviors. We studied a marked population of the Wandering Tattler Tringa incana, during a three-year period (1997–1999) on nesting grounds in south-central Alaska. Two aspects of our results stand out. First is the previously undescribed preference for tattlers to nest several kilometers removed from pre-nesting feeding areas, mostly in association with both small (kettle) lakes and running water (near small distributaries of major drainages). Second is the apparent use of the study area by cohorts of birds of different breeding status, including (1) local breeders, which defended pre-breeding foraging areas, (2) local non-breeding birds, which remained on the area but were not territorial, and (3) transients that were captured later in the season, but not seen again on the area during the season of capture. We also found that (1) birds tended to nest in clusters despite what appeared to be the ample availability of nesting habitat, (2) they employed an inconspicuous’ nesting strategy whereby neither member of a pair betrayed its presence on the nesting area, and (3) females departed the area during early chick-rearing, leaving males to tend broods.

  1. Seismicity and stress in the vicinity of Mount Spurr volcano, south central Alaska

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur D.; Page, Robert A.; Power, John A.

    1994-08-01

    Focal mechanism solutions and hypocenters for earthquakes near Mount Spurr volcano in south central Alaska reveal spatial perturbations in the regional stress field and in the maximum depth of seismicity. At the volcano, practically all the shocks during the dormant decade 1981-1991 have depths shallower than 5 km and are characterized by nearly pure normal slip. In contrast, earthquakes located outboard of the volcano concentrate in the depth range 3-18 km and exhibit predominantly strike slip, oblique reverse slip, or reverse slip. The regional stress field is characterized by subhorizontal maximum principal stress directed N 30 deg W, concordant with the direction of convergence between the North American and Pacific plates, whereas the maximum principal stress is probably more nearly vertical beneath the volcano. We suggest that the shoaling of seismicity beneath the volcano reflects localized elevation of the depth to the midcrustal transition from brittle failure to plastic flow. We attribute this localized elevation to relict magmatic heat associated with past volcanic eruptions. The available data are not sufficient to determine the cause of the suggested rotation of the maximum principal stress axis beneath the volcano; possible mechanisms include an increase in the vertical stress from the weight of the Mount Spurr massif and a decrease in the maximum horizontal stress associated with doming of the shallow crust from magmatic processes.

  2. Estuarine environments as rearing habitats for juvenile Coho Salmon in contrasting south-central Alaska watersheds

    USGS Publications Warehouse

    Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

    2013-01-01

    For Pacific salmon, estuaries are typically considered transitional staging areas between freshwater and marine environments, but their potential as rearing habitat has only recently been recognized. The objectives of this study were two-fold: (1) to determine if Coho Salmon Oncorhynchus kisutch were rearing in estuarine habitats, and (2) to characterize and compare the body length, age, condition, and duration and timing of estuarine occupancy of juvenile Coho Salmon between the two contrasting estuaries. We examined use of estuary habitats with analysis of microchemistry and microstructure of sagittal otoliths in two watersheds of south-central Alaska. Juvenile Coho Salmon were classified as estuary residents or nonresidents (recent estuary immigrants) based on otolith Sr : Ca ratios and counts of daily growth increments on otoliths. The estuaries differed in water source (glacial versus snowmelt hydrographs) and in relative estuarine and watershed area. Juvenile Coho Salmon with evidence of estuary rearing were greater in body length and condition than individuals lacking evidence of estuarine rearing. Coho Salmon captured in the glacial estuary had greater variability in body length and condition, and younger age-classes predominated the catch compared with the nearby snowmelt-fed, smaller estuary. Estuary-rearing fish in the glacial estuary arrived later and remained longer (39 versus 24 d of summer growth) during the summer than did fish using the snowmelt estuary. Finally, we observed definitive patterns of overwintering in estuarine and near shore environments in both estuaries. Evidence of estuary rearing and overwintering with differences in fish traits among contrasting estuary types refute the notion that estuaries function as only staging or transitional habitats in the early life history of Coho Salmon.

  3. Diverging Histories of the Liberty Creek and Iceberg Lake Blueschist Bodies, south central Alaska

    NASA Astrophysics Data System (ADS)

    Day, E. M.; Pavlis, T. L.; Amato, J. M.

    2011-12-01

    New studies of the Liberty Creek and Iceberg Lake blueschist bodies of south central Alaska indicate that despite structural similarities, these blueschist bodies are derived from a different protolith and were metamorphosed to blueschist facies at distinctly different times. Both blueschists are located just south of the Border Ranges Fault (BRF) within outcrop belts of the McHugh Complex, a low-grade mélange assemblage that is now known from detrital zircon studies to consist of two distinct assemblages: a Jurassic to Earliest Cretaceous assemblage and a Late Cretaceous assemblage. The BRF is a megathrust system that represents the Late Triassic-Early Jurassic initiation of southern Alaskan subduction. Large scale (1:24,000) mapping revealed similar fabric overprint histories, epitomized by a previously undescribed youngest vertical N-S trending crenulation cleavage in both blueschist bodies which implies a structural correlation despite their separation of ~100 kilometers along strike. Despite structural similarities detrital zircon studies show that the Liberty Creek and Iceberg Lake blueschists do not have a similar maximum age of deposition. Thirteen samples from the Iceberg Lake blueschist were processed, none of which produced detrital zircons. Samples from the McHugh Complex greenschists that surround the Iceberg Lake blueschist produced numerous zircons indicating a Late Jurassic (~160 Ma) maximum age of deposition. Three out of sixteen samples from the Liberty creek blueschist produced detrital zircons indicating maximum depositional ages ranging from Late Jurassic (~160.1 Ma, n=64 grains; ~152.25 Ma, n=68 grains) to Early Cretaceous (~137.1 Ma, n=95 grains). The Late Jurassic dates are consistent with maximum depositional ages determined by Amato and Pavlis (2010) for McHugh Complex rocks along Turnagain Arm near Anchorage, AK. Sisson and Onstott (1986) reported a metamorphic cooling age of 185 Ma for the Iceberg Lake blueschist, thus, although no

  4. Non-volcanic Tremor Triggered by Teleseismic Surface Waves in South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Flinchum, B. A.; Brudzinski, M. R.

    2011-12-01

    Non-volcanic tremor is a subtle ground vibration thought to be composed of a swarm of low-frequency earthquakes that represent fault slip on the interface between plates. By knowing when and where tremor is triggered, as well as when it is not triggered, we hope to grasp a better understanding of what conditions are necessary to induce fault slip. Based on recent reports of ambient tremor in South-Central Alaska during episodes of slow slip, we examined the time series during teleseismically recorded wave trains for eleven recent earthquakes with moment magnitude greater than 8.0. From these eleven events, we tested whether these events triggered NVT and where the tremor occurred. We initially performed a visual scan for tremor-like signals during incoming teleseismic phases using a 6-10 Hz bandpass filter on seismograms from stations over an area approximately 800 km by 600 km. We found five cases of triggered tremor that typically could be seen on stations such as PAX, HARP, MCK and KLU, although one additional event produced tremor that could only be seen on PAX. Next we designed an automated algorithm to both identify correlated NVT signals across several stations and locate the source of NVT. The automated system takes a few base stations where tremor signals have been seen during the visual search and then uses cross-correlation to progressively scan ten second portions of the entire teleseismic wave train at all other stations for similar bursts in NVT envelope functions. We find three events where the correlations exceed a correlation value greater than 65% at four or more stations at least 15 times during the duration of the event. The tremor locations during these three events falls into a separate cluster each time, but all occur near ambient tremor locations previously identified around the inferred eastern edge of subducting Yakutat terrane. Peak ground velocity (PGV) appears to be the primary factor for triggering tremor, with nearly all cases of

  5. LANDSAT demonstration/application and GIS integration in south central Alaska

    NASA Technical Reports Server (NTRS)

    Burns, A. W.; Derrenbacher, W.

    1981-01-01

    Automated geographic information systems were developed for two sites in Southcentral Alaska to serve as tests for both the process of integrating classified LANDSAT data into a comprehensive environmental data base and the process of using automated information in land capability/suitability analysis and environmental planning. The Big Lake test site, located approximately 20 miles north of the City of Anchorage, comprises an area of approximately 150 square miles. The Anchorage Hillside test site, lying approximately 5 miles southeast of the central part of the city, extends over an area of some 25 square miles. Map construction and content is described.

  6. Late Holocene glacial history of the Copper River Delta, coastal south-central Alaska, and controls on valley glacier fluctuations

    NASA Astrophysics Data System (ADS)

    Barclay, David J.; Yager, Elowyn M.; Graves, Jason; Kloczko, Michael; Calkin, Parker E.

    2013-12-01

    Fluctuations of four valley glaciers in coastal south-central Alaska are reconstructed for the past two millennia. Tree-ring crossdates on 216 glacially killed stumps and logs provide the primary age control, and are integrated with glacial stratigraphy, ages of living trees on extant landforms, and historic forefield photographs to constrain former ice margin positions. Sheridan Glacier shows four distinct phases of advance: in the 530s to c.640s in the First Millennium A.D., and the 1240s to 1280s, 1510s to 1700s, and c.1810s to 1860s during the Little Ice Age (LIA). The latter two LIA advances are also recorded on the forefields of nearby Scott, Sherman and Saddlebag glaciers. Comparison of the Sheridan record with other two-millennia long tree-ring constrained valley glacier histories from south-central Alaska and Switzerland shows the same four intervals of advance. These expansions were coeval with decreases in insolation, supporting solar irradiance as the primary pacemaker for centennial-scale fluctuations of mid-latitude valley glaciers prior to the 20th century. Volcanic aerosols, coupled atmospheric-oceanic systems, and local glacier-specific effects may be important to glacier fluctuations as supplemental forcing factors, for causing decadal-scale differences between regions, and as a climatic filter affecting the magnitude of advances.

  7. A Detailed Geochemical Study of Island Arc Crust: The Talkeetna Arc Section, South-central Alaska

    NASA Astrophysics Data System (ADS)

    Greene, A. R.; Debari, S. M.; Kelemen, P. B.; Clift, P. D.; Blusztajn, J.

    2002-12-01

    The Talkeetna arc section in south-central Alaska is recognized as the exposed upper mantle and crust of an accreted, Late Triassic to Middle Jurassic island arc. Detailed geochemical studies of layered gabbronorite from the middle and lower crust of this arc and a diverse suite of volcanic and plutonic rocks from the middle and upper crust provide crucial data for understanding arc magma evolution. We also present new data on parental magma compositions for the arc. The deepest level of the arc section consists of residual mantle and ultramafic cumulates adjacent to garnet gabbro and basal gabbronorite interlayered with pyroxenite. The middle crust is primarily layered gabbronorite, ranging from anorthosite to pyroxenite in composition, and is the most widespread plutonic lithology. The upper mid crust is a heterogenous assemblage of dioritic to tonalitic rocks mixed with gabbro and intruded by abundant mafic dikes and chilled pillows. The upper crust of the arc is comprised of volcanic rocks of the Talkeetna Formation ranging from basalt to rhyolite. Most of these volcanic rocks have evolved compositions (<5% MgO, Mg# <60) and overlap the composition of intermediate to felsic plutonic rocks (<3.5% MgO, Mg# <45). However, several chilled mafic rocks and one basalt have primitive characteristics (>8% MgO, Mg# >60). Ion microprobe analyses of clinopyroxene in mid-crustal layered gabbronorites have parallel REE patterns with positive-sloping LREE segments (La/Sm(N)=0.05-0.17; mean 0.11) and flat HREE segments (5-25xchondrite; mean 10xchondrite). Liquids in REE equilibrium with the clinopyroxene in these gabbronorite cumulates were calculated in order to constrain parental magmas. These calculated liquids(La/Sm(N)=0.77-1.83; mean 1.26) all fall within the range of dike and volcanic rock(La/Sm(N)=0.78-2.12; mean 1.23) compositions. However, three lavas out of the 44 we have analyzed show strong HREE depletion, which is not observed in any of the liquid compositions

  8. Limnology of Big Lake, south-central Alaska, 1983-84

    USGS Publications Warehouse

    Woods, Paul F.

    1992-01-01

    The limnological characteristics and trophic state of Big Lake in south-central Alaska were determined from the results of an intensive study during 1983-84. The study was begun in response to concern over the potential for eutrophication of Big Lake, which has experienced substantial residential development and recreational use because of its proximity to Anchorage. The east and west basins of the 1,213 square-hectometer lake were each visited 36 times during the 2-year study to obtain a wide variety of physical, chemical, and biological data. During 1984, an estimate was made of the lake's annual primary production. Big Lake was classified as oligotrophic on the basis of its annual mean values for total phosphorus (9.5 micrograms per liter), total nitrogen (209 micrograms per liter), chlorophyll-a (2.5 micrograms per liter), secchi-disc transparency (6.3 meters), and its mean daily integral primary production of 81.1 milligrams of carbon fixed per square meter. The lake was, however, uncharacteristic of oligotrophic lakes in that a severe dissolved-oxygen deficit developed within the hypolimnion during summer stratification and under winter ice cover. The summer dissolved-oxygen deficit resulted from the combination of strong and persistent thermal stratification, which developed within 1 week of the melting of the lake's ice cover in May, and the failure of the spring circulation to fully reaerate the hypolimnion. The autumn circulation did reaerate the entire water column, but the ensuing 6 months of ice and snow cover prevented atmospheric reaeration of the water column and led to development of the winter dissolved-oxygen deficit. The anoxic conditions that eventually developed near the lake bottom allowed the release of nutrients from the bottom sediments and facilitated ammonification reactions. These processes yielded hypolimnetic concentrations of nitrogen and phosphorus compounds, which were much larger than the oligotrophic concentrations measured

  9. Tectonic implications of paleomagnetic poles from Lower Tertiary Volcanic Rocks, south central Alaska

    NASA Astrophysics Data System (ADS)

    Hillhouse, John W.; Grommé, C. Sherman; Csejtey, Bela, Jr.

    1985-12-01

    We have determined the paleolatitude of lower Tertiary volcanic rocks in southern Alaska to measure possible poleward translation of the Wrangellia and the Peninsular terranes after 50 m.y. ago. Previous paleomagnetic studies have shown that in Triassic and Jurassic time these terranes were located near the equator and have moved at least 3000 km poleward relative to the North American craton. Our sample localities are in the northern Talkeetna Mountains in mildly deformed andesite and dacite flows (50.4, 51.3, 53.9, and 56.3 m.y. by K-Ar) that overlap Lower Cretaceous flysch, Lower Permian volcanic rocks of Wrangellia, and Upper Triassic pillow basalt of the Susitna terrane. Results from 26 cooling units (23 of reversed polarity and 3 of normal polarity) give a mean paleomagnetic pole at 69.5°N, 179.6°E, α95 = 12.2°. Stratigraphic sections from opposite limbs of a syncline yield directional paths that pass the fold test, satisfying a necessary condition for primary origin of the magnetization. The corresponding mean paleolatitude (76°N) of the northern Talkeetna Mountains is 8°±10° higher than the latitude predicted from the Eocene reference pole for North America. Therefore, northward drift of the Talkeetna superterrane, which is the amalgamation of the Wrangellia and Peninsular terranes during and after Middle Jurassic time, was probably complete by 50 m.y. ago. Our results are consistent with paleomagnetic poles from uppermost Cretaceous and Paleocene volcanic sequences in Denali National Park, the Lake Clark region, northern Bristol Bay region, and near McGrath. These poles generally lie south of the cratonic poles, suggesting that the region between the Kaltag, Bruin Bay, and Castle Mountain faults has rotated counterclockwise relative to North America since the early Eocene.

  10. Migration and wintering areas of glaucous-winged Gulls from south-central Alaska

    USGS Publications Warehouse

    Hatch, Shyla A.; Gill, V.A.; Mulcahy, D.M.

    2011-01-01

    We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucouswinged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter. ?? The Cooper Ornithological Society 2011.

  11. Migration And wintering areas Of Glaucous-winged Gulls From south-central Alaska

    USGS Publications Warehouse

    Hatch, Scott A.; Gill, V.A.; Mulcahy, Daniel M.

    2011-01-01

    We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucous-winged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter.

  12. Role of lake regulation on glacier fed rivers in enhancing salmon productivity: The Cook Inlet watershed south central Alaska, USA

    USGS Publications Warehouse

    Hupp, C.R.

    2000-01-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation. Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat. Copyright ?? 2000 John Wiley & Sons, Ltd.Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet

  13. Density and magnetic suseptibility values for rocks in the Talkeetna Mountains and adjacent region, south-central Alaska

    USGS Publications Warehouse

    Sanger, Elizabeth A.; Glen, Jonathan M.G.

    2003-01-01

    This report presents a compilation and statistical analysis of 306 density and 706 magnetic susceptibility measurements of rocks from south-central Alaska that were collected by U.S. Geological Survey (USGS) and Alaska Division of Geological and Geophysical Surveys (ADGGS) scientists between the summers of 1999 and 2002. This work is a product of the USGS Talkeetna Mountains Transect Project and was supported by USGS projects in the Talkeetna Mountains and Iron Creek region, and by Bureau of Land Management (BLM) projects in the Delta River Mining District that aim to characterize the subsurface structures of the region. These data were collected to constrain potential field models (i.e., gravity and magnetic) that are combined with other geophysical methods to identify and model major faults, terrane boundaries, and potential mineral resources of the study area. Because gravity and magnetic field anomalies reflect variations in the density and magnetic susceptibility of the underlying lithology, these rock properties are essential components of potential field modeling. In general, the average grain density of rocks in the study region increases from sedimentary, felsic, and intermediate igneous rocks, to mafic igneous and metamorphic rocks. Magnetic susceptibility measurements performed on rock outcrops and hand samples from the study area also reveal lower magnetic susceptibilities for sedimentary and felsic intrusive rocks, moderate susceptibility values for metamorphic, felsic extrusive, and intermediate igneous rocks, and higher susceptibility values for mafic igneous rocks. The density and magnetic properties of rocks in the study area are generally consistent with general trends expected for certain rock types.

  14. Rock-Eval pyrolysis and vitrinite reflectance results from the Sheep Creek 1 well, Susitna basin, south-central Alaska

    USGS Publications Warehouse

    Stanley, Richard G.; Lillis, Paul G.; Pawlewicz, Mark J.; Haeussler, Peter J.

    2014-01-01

    We used Rock-Eval pyrolysis and vitrinite reflectance to examine the petroleum source potential of rock samples from the Sheep Creek 1 well in the Susitna basin of south-central Alaska. The results show that Miocene nonmarine coal, carbonaceous shale, and mudstone are potential sources of hydrocarbons and are thermally immature with respect to the oil window. In the samples that we studied, coals are more organic-rich and more oil-prone than carbonaceous shales and silty mudstones, which appear to be potential sources of natural gas. Lithologically similar rocks may be present in the deeper parts of the subsurface Susitna basin located west of the Sheep Creek 1 well, where they may have been buried deeply enough to generate oil and (or) gas. The Susitna basin is sparsely drilled and mostly unexplored, and no commercial production of hydrocarbons has been obtained. However, the existence of potential source rocks of oil and gas, as shown by our Rock-Eval results, suggests that undiscovered petroleum accumulations may be present in the Susitna basin.

  15. Age-specific reproduction in female sea otters (Enhydra lutris) from south-central Alaska: analysis of reproductive tracts

    USGS Publications Warehouse

    Bodkin, J.; Mulcahy, D.; Lensink, C.

    1993-01-01

    We estimated age at sexual maturity and age-specific reproductive rates by examining carcasses and reproductive tracts from 177 female sea otters (Enhydra lutris). Carcasses were recovered from south-central Alaska, Primarily from western Prince William Sound, as a result of the T/V Exxon Valdez oit spill in 1989. We found 65% of our sample to be sexually mature. Sexual maturity was first attained at age 2. The proportion of sexually mature animals increased from 30% at age 2 to 100% at age 5. Annual reproductive rates increased from 22% at age 2 to 78% at age 5 and remained relatively stable (75-88%) through to age 15. the sex ratio (female:male) of 49 fetal sea otters was 18:37 and differed significantly from parity. Females younger than 8 tended to produce more female fetuses, while older mothers did not. Our estimates of the reproductive characteristics of female sea otters obtained by examination of reproductive tracts wre similiar to those reported in the literature based on in situ observations of marked individuals.

  16. Range overlap and individual movements during breeding season influence genetic relationships of caribou herds in south-central Alaska

    USGS Publications Warehouse

    Roffler, Gretchen H.; Adams, Layne G.; Talbot, Sandra L.; Sage, George K.; Dale, Bruce W.

    2012-01-01

    North American caribou (Rangifer tarandus) herds commonly exhibit little nuclear genetic differentiation among adjacent herds, although available evidence supports strong demographic separation, even for herds with seasonal range overlap. During 1997–2003, we studied the Mentasta and Nelchina caribou herds in south-central Alaska using radiotelemetry to determine individual movements and range overlap during the breeding season, and nuclear and mitochondrial DNA (mtDNA) markers to assess levels of genetic differentiation. Although the herds were considered discrete because females calved in separate regions, individual movements and breeding-range overlap in some years provided opportunity for male-mediated gene flow, even without demographic interchange. Telemetry results revealed strong female philopatry, and little evidence of female emigration despite overlapping seasonal distributions. Analyses of 13 microsatellites indicated the Mentasta and Nelchina herds were not significantly differentiated using both traditional population-based analyses and individual-based Bayesian clustering analyses. However, we observed mtDNA differentiation between the 2 herds (FSTM = 0.041, P

  17. Population genetic structure of moose (Alces Alces) of South-central Alaska.

    USGS Publications Warehouse

    Wilson, Robert E.; McDonough, John T.; Barboza, Perry S.; Talbot, Sandra L.; Farley, Sean D.

    2015-01-01

    The location of a population can influence its genetic structure and diversity by impacting the degree of isolation and connectivity to other populations. Populations at range margins areoften thought to have less genetic variation and increased genetic structure, and a reduction in genetic diversity can have negative impacts on the health of a population. We explored the genetic diversity and connectivity between 3 peripheral populations of moose (Alces alces) with differing potential for connectivity to other areas within interior Alaska. Populations on the Kenai Peninsula and from the Anchorage region were found to be significantly differentiated (FST= 0.071, P < 0.0001) with lower levels of genetic diversity observed within the Kenai population. Bayesian analyses employing assignment methodologies uncovered little evidence of contemporary gene flow between Anchorage and Kenai, suggesting regional isolation. Although gene flow outside the peninsula is restricted, high levels of gene flow were detected within the Kenai that is explained by male-biased dispersal. Furthermore, gene flow estimates differed across time scales on the Kenai Peninsula which may have been influenced by demographic fluctuations correlated, at least in part, with habitat change.

  18. Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Potter, Christopher J.; Shah, Anjana K.; Stanley, Richard G.; Haeussler, Peter J.; Saltus, Richard W.

    2015-01-01

    The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

  19. Paleomagnetism of Cretaceous and Paleocene sedimentary rocks across the Castle Mountain Fault, south central Alaska

    NASA Astrophysics Data System (ADS)

    Stamatakos, John A.; Kodama, K. P.; Vittorio, L. F.; Pavlis, T. L.

    Paleomagnetic and rock magnetic analyses on 217 samples from 13 sites in the Paleocene Chickaloon Formation south of the Castle Mountain Fault and 111 samples from 9 sites in the coeval, but lithologically distinct, Arkose Ridge Formation north of this fault indicate that these rocks contain a pre-folding magnetization carried by fine grained (<1.0μm) single domain magnetite. Secondary magnetizations are common, possibly as the result of the presence of authigenic or hydrothermal pyrrhotite. Although characteristic magnetizations were isolated for the Chickaloon and Arkose Ridge rocks, the best results were obtained from demagnetization plane analysis which estimates the location of the paleomagnetic pole for the Chickaloon Formation at 50.5°N, 277.2°E, δm = 12.2°, δP = 7.77deg;, and a paleomagnetic pole for the Arkose Ridge Formation at 60.4°N, 138.6°E, δm = 11.6°, δp = 6.4°. These results suggest that there is no paleomagnetically discernible latitudinal offset across the Castle Mountain Fault since Paleocene time, but that both the Chickaloon and Arkose Ridge rocks, as part of the Peninsular terrane, originated approximately 1600±1200 km south of their present position with respect to North America. One possible explanation of these data is that the Peninsular terrane was accreted to North America at mid-latitudes in the Cretaceous and was subsequently translated northward by right-lateral strike-slip faulting parallel to the North American margin. Hence, the Arkose Ridge and Chickaloon results may be indicative of the cumulative right-hand displacement occurring on these faults since Paleocene time. However, a calculation using the pole to the small circle fit of the present-day curvature of the Tintina-Northern Rocky Mountain Trench and Denali fault systems, and the maximum amount of structurally estimated offset across these fault systems, indicates that motion on these faults can account for no more than half of the paleomagnetically observed

  20. Field-trip guide to volcanic and volcaniclastic deposits of the lower Jurassic Talkeetna formation, Sheep Mountain, south-central Alaska

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Blodgett, Robert B.

    2006-01-01

    This guide provides information for a one-day field trip in the vicinity of Sheep Mountain, just north of the Glenn Highway in south-central Alaska. The Lower Jurassic Talkeetna Formation, consisting of extrusive volcanic and volcaniclastic sedimentary rocks of the Talkeetna arc complex, is exposed on and near Sheep Mountain. Field-trip stops within short walking distance of the Glenn Highway (approximately two hours’ drive from Anchorage) are described, which will be visited during the Geological Society of America Penrose meeting entitled Crustal Genesis and Evolution: Focus on Arc Lower Crust and Shallow Mantle, held in Valdez, Alaska, in July 2006. Several additional exposures of the Talkeetna Formation on other parts of Sheep Mountain that would need to be accessed with longer and more strenuous walking or by helicopter are also mentioned.

  1. Genetic characterization of Kenai brown bears (Ursus arctos): Microsatellite and mitochondrial DNA control region variation in brown bears of the Kenai Peninsula, south central Alaska

    USGS Publications Warehouse

    Jackson, J.V.; Talbot, S.L.; Farley, S.

    2008-01-01

    We collected data from 20 biparentally inherited microsatellite loci, and nucleotide sequence from the maternally inherited mitochondrial DNA (mtDNA) control region, to determine levels of genetic variation of the brown bears (Ursus arctos L., 1758) of the Kenai Peninsula, south central Alaska. Nuclear genetic variation was similar to that observed in other Alaskan peninsular populations. We detected no significant inbreeding and found no evidence of population substructuring on the Kenai Peninsula. We observed a genetic signature of a bottleneck under the infinite alleles model (IAM), but not under the stepwise mutation model (SMM) or the two-phase model (TPM) of microsatellite mutation. Kenai brown bears have lower levels of mtDNA haplotypic diversity relative to most other brown bear populations in Alaska. ?? 2008 NRC.

  2. Frozen debris lobes, permafrost slope instability, and a potential infrastructure hazard in the south-central Brooks Range of Alaska

    NASA Astrophysics Data System (ADS)

    Daanen, R. P.; Darrow, M.; Grosse, G.; Jones, B. M.

    2012-12-01

    Here we report on investigations carried out at unusual debris mass-movement features (frozen debris lobes) on permafrost slopes in the south central portion of the Brooks Range of northern Alaska. The features under investigation are located in mountainous terrain near the southern border of continuous permafrost. The frozen debris lobes consist mainly of boulders, cobles, platy gravel sand and silt frozen debris derived from weathering mountain tops. The general dimensions of these lobes are either lobate or tongue shaped with widths up to 500 m and lengths up to 1200 m. In accumulation zones where slopes converge, the debris slowly moves as solifluction lobes, mud flows and potentially sliding toward the valley. These features were previously referred to as stable rock glaciers in the past, as evidenced by a dense cover of vegetation, and exhibiting no known downslope movement. Our investigations however, have shown that these features are indeed moving downslope as a result of creep, slumping, viscous flow, blockfall and leaching of fines in the summer; and in cold seasons by creep and sliding of frozen sediment slabs. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. Ground-based measurements on one frozen debris-lobe over three years (2008-2010) revealed average movement rates of approximately 1 cm day-1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. Current observations , through lidar, ifsar, insar and ground based measurements using boreholes, geophysics and repeat photography of these features show an increase in movement activity that could be the result of rising summer temperatures in the region. Warming of ice rich permafrost slopes and frozen debris lobes in the Brooks Range pose a direct threat to the

  3. Role of lake regulation on glacier-fed rivers in enhancing salmon productivity: the Cook Inlet watershed, south-central Alaska, USA

    NASA Astrophysics Data System (ADS)

    Dorava, Joseph M.; Milner, Alexander M.

    2000-10-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation.Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat.

  4. Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

    NASA Astrophysics Data System (ADS)

    Daanen, R. P.; Grosse, G.; Darrow, M. M.; Hamilton, T. D.; Jones, B. M.

    2012-05-01

    We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008-2010) revealed average movement rates of approximately 1 cm day-1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation

  5. Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

    USGS Publications Warehouse

    Daanen, R.P.; Grosse, G.; Darrow, M.M.; Hamilton, T.D.; Jones, Benjamin M.

    2012-01-01

    We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008–2010) revealed average movement rates of approximately 1 cm day−1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation

  6. Effects of the earthquake of March 27, 1964, on air and water transport, communications, and utilities systems in south-central Alaska: Chapter B in The Alaska earthquake, March 27, 1964: effects on transportation, communications, and utilities

    USGS Publications Warehouse

    Eckel, Edwin B.

    1967-01-01

    The earthquake of March 27, 1964, wrecked or severely hampered all forms of transportation, all utilities, and all communications systems over a very large part of south-central Alaska. Effects on air transportation were minor as compared to those on the water, highway, and railroad transport systems. A few planes were damaged or wrecked by seismic vibration or by flooding. Numerous airport facilities were damaged by vibration or by secondary effects of the earthquake, notably seismic sea and landslide-generated waves, tectonic subsidence, and compaction. Nearly all air facilities were partly or wholly operational within a few hours after the earthquake. The earthquake inflicted enormous damage on the shipping industry, which is indispensable to a State that imports fully 90 percent of its requirements—mostly by water—and whose largest single industry is fishing. Except for those of Anchorage, all port facilities in the earthquake-affected area were destroyed or made inoperable by submarine slides, waves, tectonic uplift, and fire. No large vessels were lost, but more than 200 smaller ones (mostly crab or salmon boats) were lost or severely damaged. Navigation aids were destroyed, and hitherto well-known waterways were greatly altered by uplift or subsidence. All these effects wrought far-reaching changes in the shipping economy of Alaska, many of them to its betterment. Virtually all utilities and communications in south-central Alaska were damaged or wrecked by the earthquake, but temporary repairs were effected in remarkably short times. Communications systems were silenced almost everywhere by loss of power or by downed lines; their place was quickly taken by a patchwork of self-powered radio transmitters. A complex power-generating system that served much of the stricken area from steam, diesel, and hydrogenerating plants was disrupted in many places by vibration damage to equipment and by broken transmission lines. Landslides in Anchorage broke gas

  7. A deglacial and Holocene record of climate variability in south-central Alaska from stable oxygen isotopes and plant macrofossils in peat

    USGS Publications Warehouse

    Jones, Miriam C.; Wooller, Matthew J.; Peteet, Dorothy M.

    2014-01-01

    We used stable oxygen isotopes derived from bulk peat (δ18OTOM), in conjunction with plant macrofossils and previously published carbon accumulation records, in a ∼14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in δ18OTOM values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher δ18OTOM values) during the Bølling-Allerød, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern δ18O values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower δ18OTOM values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that δ18OTOM values in peat can be applied toward understand large-scale shifts in atmospheric circulation

  8. Structural geology and kinematics associated with the collision of the Wrangellia composite terrane and North America, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Bier, Sara Elizabeth

    The collision of the Insular superterrane, and thus, the Wrangellia composite terrane (WCT), with the Mesozoic margin of North America is one of the most important, yet enigmatic events in the tectonic history of North American cordillera. The location and therefore the nature of the collision of the Insular superterrane with North America remains controversial. In southern Alaska, the suture zone between the WCT and North America consists of the Kahiltna assemblage, Jurassic-Cretaceous submarine fan deposits. Structural investigation of the Kahiltna assemblage provides additional data on the kinematics of the collision and suggests an oblique collision with a significant component of right-lateral shearing. The first study of the dissertation presents the results across a transect at the northern end of Broad Pass where the depositional and deformational history of three tectonostratigraphic units enables determination of the tectonic evolution of the suture zone. The Reindeer Hills exposes melange units that include oceanic lithologies and represent a remnant of an accretionary complex that formed during subduction prior to the collision of the WCT. Structures within the Kahiltna assemblage in the Talkeetna Mountains indicate oblique northwest-directed thrusting and right-lateral shear during the collision of the WCT. The Jack River conglomerate, a fluvial clast-supported conglomerate unconformably overlies the Reindeers Hills melange and represents uplift, erosion, and deposition late in the collision. The second study is on the other side of Broad Pass, in the southern Alaska Range, and consists of a composite transect across the Peters and Dutch Hills and Chelatna Lake. Horizontal stretching lineations and steeply-dipping foliation indicate that deformation occurred during transpression as a result of an oblique collision. Strain analysis of pressure shadows indicate a counterclockwise rotation of the extension direction and thus, right-lateral shearing during

  9. Kittlitz's and Marbled Murrelets in Kenai Fjords National Park, South-Central Alaska: At-Sea Distribution, Abundance, and Foraging Habitat, 2006-08

    USGS Publications Warehouse

    Arimitsu, M.L.; Piatt, J.F.; Romano, Marc D.; Madison, E.N.; Conaway, J.S.

    2010-01-01

    Kittlitz's murrelets (Brachyramphus brevirostris) and marbled murrelets (B. marmoratus) are small diving seabirds and are of management concern because of population declines in coastal Alaska. In 2006-08, we conducted a study in Kenai Fjords National Park, south-central Alaska, to estimate the recent population size of Brachyramphus murrelets, to evaluate productivity based on juvenile to adult ratios during the fledgling season, and to describe and compare their use of marine habitat. We also attempted a telemetry study to examine Kittlitz's murrelet nesting habitat requirements and at-sea movements. We estimated that the Kittlitz's murrelet population was 671 ? 144 birds, and the marbled murrelet population was 5,855 ? 1,163 birds. Kittlitz's murrelets were limited to the heads of three fjords with tidewater glaciers, whereas marbled murrelets were more widely distributed. Population estimates for both species were lower in 2007 than in 2006 and 2008, possibly because of anomalous oceanographic conditions that may have delayed breeding phenology. During late season surveys, we observed few hatch-year marbled murrelets and only a single hatch-year Kittlitz's murrelet over the course of the study. Using radio telemetry, we found a likely Kittlitz's murrelet breeding site on a mountainside bordering one of the fjords. We never observed radio-tagged Kittlitz's murrelets greater than 10 kilometer from their capture sites, suggesting that their foraging range during breeding is narrow. We observed differences in oceanography between fjords, reflecting differences in sill characteristics and orientation relative to oceanic influence. Acoustic biomass, a proxy for zooplankton and small schooling fish, generally decreased with distance from glaciers in Northwestern Lagoon, but was more variable in Aialik Bay where dense forage fish schools moved into glacial areas late in the summer. Pacific herring (Clupea pallasii), capelin (Mallotus villosus) and Pacific sand lance

  10. A Deglacial and Holocene Record of Climate Variability in South-Central Alaska from Stable Oxygen Isotopes and Plant Macrofossils in Peat

    NASA Technical Reports Server (NTRS)

    Jones, Miriam C.; Wooller, Matthew; Peteet, Dorothy M.

    2014-01-01

    We used stable oxygen isotopes derived from bulk peat (delta-O-18(sub TOM) in conjunction with plant macrofossils and previously published carbon accumulation records, in a approximately14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in delta-O-18(sub TOM) values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher delta-O-18(sub TOM) values) during the Bolling-Allerod, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern delta-O-18 values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower delta-O-18(sub TOM) values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that delta-O-18(sub TOM) values in peat can be applied

  11. Landslide Hazard Mapping Using Ground-based Interferometric Radar in the Fjords of South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Balazs, M. S.; Meyer, F. J.; Bollian, T.; Wolken, G. J.; Prakash, A.

    2013-12-01

    The cities of Seward and Whittier, Alaska are situated at the base of steep walls within two fjords located on the Kenai Peninsula. Historic events have shown that the combination of terrain, geology, and vegetation are factors which can lead to significant events of erosion in the surrounding slopes during periods of heavy rainfall. While other remote sensing techniques have been shown to be useful for accessing landslide hazards, local surface processes may be better understood to create more accurate hazard maps and predictive models by using data gained from interferometric radar. To gain perspective into where, and at which speed, slopes are deforming, we utilize the GPRI-2 terrestrial interferometric radar system which transmits signals in the Ku band. The GPRI-2 portable radar unit has several advantages to space-borne radar, including relative freedom of site selection and regions to target, ability to determine temporal baselines, and repeat acquisitions which can be collected with a zero spatial-baseline. There are however, problems which need to be addressed when using such a system in the fjord environments, and in particular for monitoring slope deformation in these areas. Foremost, the noise that is attributed to the atmosphere is of great concern as it is sometimes required to position the radar several kilometers away from the target, across open water. We offer our results of correcting for this interference and report the results. Secondly, we address the issue of repeat acquisitions over long periods of time, which is needed to detect movements in the slope, and report on the decorrelation of the signal in the various land cover types in the study areas. Finally, we offer suggestions of the usefulness of such a system to detect slope deformation in similar environments.

  12. Geochemistry of siliciclastic rocks in the Peninsular, Chugach, and Prince William terranes: Implications for the tectonic evolution of south central Alaska

    SciTech Connect

    Gilbert, S.A.; Casey, J.F. . Dept. of Geosciences); Bradley, D. . Branch of Alaskan Geology); Kusky, T. . Dept. of Geology)

    1992-01-01

    According to some interpretations, south-central Alaska consists of a series of unrelated terranes juxtaposed by dominantly strike-slip motions some time after formation. Alternatively, these so-called terranes may be related components of a seaward-facing arc, forearc, and accretionary prism. To shed new light on the tectonic history of this area, 150 samples of siliciclastic rocks were analyzed for major, trace, and rare earth elements (REE). Shales were sampled from the Upper Cretaceous Matanuska and Paleogene Chickaloon Fms. of the Peninsular Terrane (forearc basin); argillaceous melange matrix from the Mesozoic McHugh Complex and slate from turbidites of the Upper Cretaceous Valdez Group of the Chugach Terrane (landward part of accretionary prism); and slate from turbidites of the Paleogene Orea Group of the Prince William Terrane (seaward part of accretionary prism). One tectonic model that may fit these geochemical data requires an early linkage between the Peninsular and Chugach-Prince William composite terranes. The geochemical signatures suggest that the McHugh Complex was derived from a mafic volcanic source and may represent an early accretionary stage of sediments derived from an oceanic arc. The progressive continental enrichment of the Valdez and Orca Groups may reflect later accretionary processes during and/or after the collision of the Talkectna arc with the North American continent. The similar increasingly continental source documented in the geochemistry of the forearc basin shales of the Matanuska and Chickaloon Fms. may suggest: that the presently defined Peninsular, Chugach, and Prince William terranes collectively represent one continuously evolving, seaward facing arc, forearc, and accretionary prism complex.

  13. Assessment of the Coal-Bed Gas Total Petroleum System in the Cook Inlet-Susitna region, south-central Alaska

    USGS Publications Warehouse

    Rouse, William A.; Houseknecht, David W.

    2012-01-01

    The Cook Inlet-Susitna region of south-central Alaska contains large quantities of gas-bearing coal of Tertiary age. The U.S. Geological Survey in 2011 completed an assessment of undiscovered, technically recoverable coal-bed gas resources underlying the Cook Inlet-Susitna region based on the total petroleum system (TPS) concept. The Cook Inlet Coal-Bed Gas TPS covers about 9,600,000 acres and comprises the Cook Inlet basin, Matanuska Valley, and Susitna lowland. The TPS contains one assessment unit (AU) that was evaluated for coal-bed gas resources between 1,000 and 6,000 feet in depth over an area of about 8,500,000 acres. Coal beds, which serve as both the source and reservoir for natural gas in the AU, were deposited during Paleocene-Pliocene time in mires associated with a large trunk-tributary fluvial system. Thickness of individual coal beds ranges from a few inches to more than 50 feet, with cumulative coal thickness of more than 800 feet in the western part of the basin. Coal rank ranges from lignite to subbituminous, with vitrinite reflectance values less than 0.6 percent throughout much of the AU. The AU is considered hypothetical because only a few wells in the Matanuska Valley have tested the coal-bed reservoirs, so the use of analog coal-bed gas production data was necessary for this assessment. In order to estimate reserves that might be added in the next 30 years, coal beds of the Upper Fort Union Formation in the Powder River Basin of Wyoming and Montana were selected as the production analog for Tertiary coal beds in the Cook Inlet-Susitna region. Upper Fort Union coal beds have similar rank (lignite to subbituminous), range of thickness, and coal-quality characteristics as coal beds of the Tertiary Kenai Group. By use of this analog, the mean total estimate of undiscovered coal-bed gas in the Tertiary Coal-Bed Gas AU is 4.674 trillion cubic feet (TCF) of gas.

  14. Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska

    USGS Publications Warehouse

    Wallace, Kristi; Coombs, Michelle L.; Hayden, Leslie A.; Waythomas, Christopher F.

    2014-01-01

    Bluffs along the Hayes River valley, 31 km northeast and 40 km downstream from Hayes Volcano, reveal volcanic deposits that shed new light on its eruptive history. Three thick (>10 cm) and five thin (<10 cm) tephra-fall deposits are dacitic in whole rock composition and contain high proportions of amphibole to pyroxene and minor biotite and broadly correlate to Hayes tephra set H defined by earlier investigators. Two basal ages for the tephra-fall sequence of 3,690±30 and 3,750±30 14C yr B.P. are also consistent with the Hayes tephra set H timeframe. Distinguishing among Hayes tephra set H units is critical because the set is an important time-stratigraphic marker in south-central Alaska and this section provides a new reference section for Hayes tephra set H. Analysis of Fe-Ti oxide grains in the tephras shows promise for identifying individual Hayes deposits. Beneath the dacitic tephra sequence lies an older, poorly sorted tephra (tephra A) that contains dacite and rhyolite lapilli and whose basal age is 4,450±30 14C yr B.P. Immediately below the tephra-fall sequence (Unit III) lies a series of mass-flow deposits that are rich in rhyodacitic clasts (Unit II). Below Unit II and possibly coeval with it, is a 20–30 m thick pumiceous pyroclastic-flow deposit (Unit I) that extends to the valley floor. Here informally named the Hayes River ignimbrite, this deposit contains pumice clasts of rhyolite with quartz, sanidine, plagioclase, and biotite phenocrysts, an assemblage that is unique among known Quaternary volcanic products of Hayes and other Alaskan volcanoes. Units I, II, and tephra A of Unit III represent at least two previously unrecognized eruptions of Hayes Volcano that occurred prior to ~3,700 yr B.P. No compositionally equivalent distal tephra deposits correlative with Hayes Volcano rhyodacites or rhyolites have yet been identified, perhaps indicating that some of these deposits are pre-Holocene, and were largely removed by glacial ice during the last

  15. Part I: Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II: Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Robertson, Peter Benjamin

    Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin system in south-central Alaska. Strata of the Appalachian foreland basin system preserve the dynamic history of orogenesis and sediment dispersal along the east Laurentian margin, recording multiple episodes of deformation and basin development during Paleozoic time. A well-exposed, >600 m thick measured stratigraphic section of the Pine Mountain thrust sheet at Pound Gap, Kentucky affords one of the most complete exposures of Upper Devonian through Middle Pennsylvanian strata in the basin. These strata provide a window into which the foreland basin's development during two major collisional events known as the Acadian-Neoacadian and the Alleghanian orogenies can be observed. Lithofacies analysis of four major sedimentary successions observed in hanging wall strata record the upward transition from (1) a submarine deltaic fan complex developed on a distal to proximal prodelta in Late Devonian to Middle Mississippian time, to (2) a Middle to Late Mississippian carbonate bank system developed on a slowly subsiding, distal foreland ramp, which was drowned by (3) Late Mississippian renewed clastic influx to a tidally influenced, coastal deltaic complex to fluvial delta plain system unconformably overlain by (4) a fluvial braided river complex

  16. The Development of Three-Dimensional Gravity Inversion Software Applied to the Location and Geometry of the Border Ranges Fault System, South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Cardenas, R.; Doser, D. I.; Mankhemthong, N.; Baker, M. R.

    2012-12-01

    Summary The Border Ranges Fault (BRFS) system bounds the Cook Inlet and Susitna Basins, an important petroleum province within south-central Alaska. The inversion utilizes gravity data constrained with geophysical, borehole, and surface geological information. The gravity inversion software was developed and tested by comparing and verifying several plausible structural models using several layers of geologic structure along the BRFS. The novel inversion approach involves directly modeling known geology, initially free-air corrected data, and revising a priori uncertainties on the geologic model to allow comparisons to alternative interpretations. Previous modeling of the BRFS using geophysical data has been limited due to the complexity of local geology and structure, both of shallow crustal features and the deeper subduction zone. Since this inversion is based on a sequence of gridded surfaces, it is feasible to develop software to help build these gridded geologic models. The gravity surveys are used in conjunction with known topology to create gridded surfaces. The software uses a Generalized, Nonlinear Least-Squares criterion to calculate the density solution of each gridded surface based on forward computations involving semi-infinite vertical line elements. The user has the capacity to observe the gravity misfit and make adjustments to the "a priori" information upon careful examination of each computed structural model. By varying several input parameters, the user can yield a range of plausible density models for making comparisons to several interpretations. Forward Model Computations The gravitational contributions are computed using a geophysics formulation, namely the vertical line element. g = πR2Gρ( x2 + y2 + z2)-1/2 Each line element is semi-infinite and extends from the top to the bottom of each structural layer. The contribution of the body to the gravity measurement will be computed as a volume integral and added to the overall contributions of

  17. Software Development for a Three-Dimensional Gravity Inversion and Application to Study of the Border Ranges Fault System, South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Cardenas, R.; Doser, D. I.; Baker, M. R.

    2011-12-01

    Summary The Border Ranges Fault (BRFS) system bounds the Cook Inlet and Susitna Basins, an important petroleum province within south-central Alaska. An initial research goal is to test several plausible models of structure along the Border Ranges Fault System by developing a novel, 3D inversion software package. The inversion utilizes gravity data constrained with geophysical, borehole, and surface geological information. The novel inversion approach involves directly modeling known geology, initially free-air corrected data, and revising a priori uncertainties on the geologic model to allow comparisons to alternative interpretations. This technique to evaluate 3D structure in regions of highly complex geology can be applied in other studies of energy resources. The software reads an ASCII text file containing the latitude, longitude, elevation, and Free Air anomalies of each gravity station as well as gridded surface files of known topology. The contributions of each node in the grid are computed in order to compare the theoretical gravity calculations from a forward model to the gravity observations. The computation of solutions to the "linearized" inversion yields a range of plausible densities. The user will have the option of varying body proportions and dimensions to compare variations in density for changing depths of the gridded surface. Introduction Previous modeling of the BRFS using geophysical data has been limited due to the complexity of local geology and structure, both of shallow crustal features and the deeper subduction zone. Since the inversion is based on a sequence of gridded surfaces, it is feasible to develop software to help build these gridded geologic models. Without a way to modify grid surface elevations, density, and magnetic susceptibility in real time, the inversion process for the geologist would be highly nonlinear and poorly constrained, especially in structural geology this complex. Without a basic understanding of the geometry of

  18. Part I: Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II: Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Robertson, Peter Benjamin

    Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin system in south-central Alaska. Strata of the Appalachian foreland basin system preserve the dynamic history of orogenesis and sediment dispersal along the east Laurentian margin, recording multiple episodes of deformation and basin development during Paleozoic time. A well-exposed, >600 m thick measured stratigraphic section of the Pine Mountain thrust sheet at Pound Gap, Kentucky affords one of the most complete exposures of Upper Devonian through Middle Pennsylvanian strata in the basin. These strata provide a window into which the foreland basin's development during two major collisional events known as the Acadian-Neoacadian and the Alleghanian orogenies can be observed. Lithofacies analysis of four major sedimentary successions observed in hanging wall strata record the upward transition from (1) a submarine deltaic fan complex developed on a distal to proximal prodelta in Late Devonian to Middle Mississippian time, to (2) a Middle to Late Mississippian carbonate bank system developed on a slowly subsiding, distal foreland ramp, which was drowned by (3) Late Mississippian renewed clastic influx to a tidally influenced, coastal deltaic complex to fluvial delta plain system unconformably overlain by (4) a fluvial braided river complex

  19. Ordovician sponges from west-central and east-central Alaska and western Yukon Territory, Canada

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Britt, B.B.

    2008-01-01

    Moderate collections of fossil sponges have been recovered over a several-year period from a few scattered localities in west-central and east-central Alaska, and from westernmost Yukon Territory of Canada. Two fragments of the demosponge agelasiid cliefdenellid, Cliefdenella alaskaensis Stock, 1981, and mostly small unidentifiable additional fragments were recovered from a limestone debris flow bed in the White Mountain area, McGrath A-4 Quadrangle in west-central Alaska. Fragments of the agelasiid actinomorph girtyocoeliids Girtyocoeliana epiporata (Rigby & Potter, 1986) and Girtyocoelia minima n. sp., plus a specimen of the vaceletid colospongiid Corymbospongia amplia Rigby, Karl, Blodgett & Baichtal, 2005, were collected from probable Ashgillian age beds in the Livengood B-5 Quadrangle in east-central Alaska. A more extensive suite of corymbospongiids, including Corymbospongia betella Rigby, Potter & Blodgett, 1988, C. mica Rigby & Potter, 1986, and C.(?) perforata Rigby & Potter, 1986, along with the vaceletiid colospongiids Pseudo-imperatoria minima? (Rigby & Potter, 1986), and Pseudoimperatoria media (Rigby & Potter, 1986), and with the heteractinid Nucha naucum? Pickett & Jell, 1983, were recovered from uppermost part of the Jones Ridge Limestone (Ashgillian), on the south flank of Jones Ridge, in the Sheep Mountain Quadrangle, in westernmost Yukon Territory, Canada. The fossil sponges from the McGrath A-4 and Livengood B-5 quadrangles were recovered from attached Siberian terranes, and those from the Sheep Mountain Quadrangle were recovered from an allochthonous Laurentian terrane in the Yukon Territory.

  20. Placer tin deposits in central Alaska

    USGS Publications Warehouse

    Chapman, Robert Mills; Coats, Robert Roy; Payne, Thomas G.

    1963-01-01

    Placer tin, in the form of cassiterite (Sn02) and (or) tinstone (fragments including cassiterite and some vein or rock material), is known or reported in deposits that have been prospected or mined for placer gold in four areas adjacent to the Yukon River in central Alaska, 120 to 240 miles west of Fairbanks. These areas are: the Morelock Creek area, on the north side of the Yukon River about 30 miles upstream from Tanana; the Moran Dome area, about 16 miles north of the Yukon River and 25 miles northwest of Tanana; the Mason Creek area, on the north side of the Yukon River about 36 miles west of Tanana; and the Ruby-Long area, on the south side of the Yukon River near Ruby and about 40 miles east of Galena. The only extensive placer mining in these areas has been in the Ruby-Long area. Other placer deposits including some cassiterite are known in central Alaska but are not discussed in this report. Bedrock in these areas is predominantly schist of various types with some associated greenstone and other metamorphic rocks. Some granite is exposed in the Moran Dome and Ruby-Long areas and in areas close to Morelock and Mason Creeks. Barren, milky quartz veins and veinlets transecting the metamorphic rocks are common. No cassiterite was found in the bedrock, and no bedrock source of the tin has been reported. In the Moran Dome and Mason Creek areas, and in part of the Ruby-Long area, tourmaline is present in the rocks of the tin-bearing drainage basins, and apparently absent elsewhere in these areas. The placer deposits are in both valley floor and bench alluvium, which are predominantly relatively thin, rarely exceeding a thickness of 30 feet. Most of the alluvium deposits are not perennially frozen. In the Morelock Creek area tin-bearing deposits are 5 to 5? miles above the mouth of the creek, and meager evidence indicates that cassiterite and gold are present in Morelock Creek valley and some of the tributaries both upstream and downstream from these deposits. The

  1. 76 FR 45217 - Fisheries of the Exclusive Economic Zone Off Alaska; Central Gulf of Alaska Rockfish Program...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ... Economic Zone Off Alaska; Central Gulf of Alaska Rockfish Program; Amendment 88 AGENCY: National Marine... submitted Amendment 88 to the Fishery Management Plan for Groundfish of the Gulf of Alaska (FMP) for review... gains realized under the Rockfish Pilot Program and viability of the Gulf of Alaska fisheries....

  2. Structural evolution of the Port Wells gold mining district, Prince William Sound, south central Alaska: Implications for the origin of the gold lodes

    NASA Astrophysics Data System (ADS)

    Stuwe, K.

    1986-10-01

    Data collected in the Port Wells gold mining district, Alaska, indicate several stages in the structural history of the district. The first stage was the accretion and associated deformation of the Valdez group flysch sequence at the end of the Cretaceous. The deformation of the semilithified rocks included two folding phases forming isoclinal NE-SW-striking and SE-vergent folds during a D1 phase, and minor open warps in NW-SE direction during a D2 phase. Intrusion of early Oligocene (36 Ma) calc-alkaline granitoids followed deformation and was terminated by the emplacement of aplitic dikes. The major fracturing processes in both the granitoids and the country rocks occurred subsequently, probably during the uplift of the Chugach mountains in the late Tertiary. Several generations of epigenetic gold-bearing quartz veins were emplaced along the fractures at a later stage. Due to the significant time gap between peak metamorphism and mineralization, the metamorphic secretion model proposed for the vein formation is reconsidered.

  3. Stream-sediment samples reanalyzed for major, rare earth, and trace elements from seven 1:250,000-scale quadrangles, south-central Alaska, 2007-09

    USGS Publications Warehouse

    Gamble, Bruce M.; Bailey, Elizabeth A.; Shew, Nora B.; Labay, Keith A.; Schmidt, Jeanine M.; O'Leary, Richard M.; Detra, David E.

    2010-01-01

    During the 1960s through the 1980s, the U.S. Geological Survey conducted reconnaissance geochemical surveys of drainage basins throughout most of the Iliamna, Lake Clark, Lime Hills, and Talkeetna 1:250,000-scale quadrangles and parts of the McGrath, Seldovia, and Tyonek 1:250,000-scale quadrangles in Alaska. These geochemical surveys provide data necessary to assess the potential for undiscovered mineral resources and provide data that may be used to determine regional-scale element baselines. This report provides new data for 1,075 of the previously collected stream-sediment samples. The new analyses include a broader spectrum of elements and provide data that are more precise than the original analyses. All samples were analyzed for arsenic by hydride generation atomic absorption spectrometry, for gold, palladium, and platinum by inductively coupled plasma-mass spectrometry after lead button fire assay separation, and for a suite of 55 major, rare earth, and trace elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry after sodium peroxide sinter at 450 degrees Celsius.

  4. Relative sea-level response to Little Ice Age ice mass change in south central Alaska: Reconciling model predictions and geological evidence

    NASA Astrophysics Data System (ADS)

    Barlow, Natasha L. M.; Shennan, Ian; Long, Antony J.

    2012-01-01

    Integration of geological data and glacio-isostatic adjustment (GIA) modelling shows that it is possible to decouple complex mechanisms of relative sea-level (RSL) change in a tectonically active glacial environment. We model a simplest solution in which RSL changes in upper Cook Inlet, Alaska, are a combination of the interplay of tectonic and isostatic processes driven by the unique rheology of this tectonically active location. We calculate interseismic uplift during latter part of the penultimate earthquake cycle to vary from 0.3 to 0.7 mm/yr. Diatom based reconstructions of RSL from tidal marsh sediment sequences coupled with detailed age models, from AD 1400 to the AD 1964 great earthquake, show deviations from a purely tectonically driven model of regional RSL. Glacial isostatic modelling, constrained by GPS data, predicts up to 70 cm sea-level change due to mountain glacier mass balance changes during the Little Ice Age. Misfits between the GIA model predictions and RSL reconstructions in the 19th and 20th century highlight that the tidal marshes of upper Cook Inlet potentially record a hemispheric-wide acceleration in sea level and that other more complex Earth process combinations may contribute to regional RSL change.

  5. Insect-related tree mortality in south-central Alaska may be controlled by prior drought stress as indicated by δ13C and δ18O in tree rings

    NASA Astrophysics Data System (ADS)

    Miller, A. E.; Csank, A. Z.; Sherriff, R.; Berg, E.; Welker, J. M.

    2012-12-01

    Increasing temperatures at high latitudes have resulted in reduced growth and increased mortality across large areas of the northern boreal forest. A recent spruce beetle outbreak that killed over 1.5M ha of trees in south-central and southwest Alaska is thought to have been triggered by a series of warm summers that facilitated the accumulation of the beetle populations in already-physiologically stressed trees. Whether trees killed by the spruce beetle (Dendroctonus rufipennis) showed evidence of temperature-induced drought stress prior to death was examined by using tree-ring chronologies and δ13C & δ18O isotopic values in cellulose from paired live and dead trees at four sites in south-central Alaska. We also tested whether surviving trees differed from dead trees in their growth response and temperature sensitivity. Our results indicate that the trees killed by spruce beetle show reduced radial growth up to 20 years prior to death, relative to surviving trees, and that this is true across age and DBH classes (n=48 pairs; P<0.004). A moving correlation between June mean temperature and live and dead tree-growth indices from a mesic forest site shows that whereas growth in surviving trees was only weakly correlated with temperature until roughly 10 years before the beetle outbreak, growth in the dead trees was positively correlated with spring-summer temperatures, particularly June mean temperature (r=0.5; P<0.05) for several decades before. Approximately 10 years prior to tree death, growth in the dead trees became decoupled from temperature. This is in contrast to δ13C & δ18O values in dead trees from the site that show a strong positive correlation between δ13C and mean June maximum temperature (r2 = 0.35; P<0.001), and with δ18O later in the summer (June-July maximum temperature; r2 = 0.26; P<0.001). However, δ13C values showed a slightly higher correlation with spring temperatures (March-May average temperature; r2 = 0.36; P<0.001). In the 10 years

  6. Geochemical evidence for the origin of late Quaternary loess in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.

    2006-01-01

    Loess is extensive in central Alaska, but there are uncertainties about its source and the direction of paleo-winds that deposited it. Both northerly and southerly winds have been inferred. The most likely sources of loess are the Tanana River (south), the Nenana River (southeast), and the Yukon River (north). Late Quaternary loess in central Alaska has immobile trace-element compositions (Cr/Sc, Th/Ta, Th/ Sc, Th/U, Eu/Eu*, GdN/YbN) that indicate derivation mostly from the Tanana River. However, other ratios (As/Sb, Zr/Hf, LaN/YbN) and quantitative modeling indicate that the Yukon River was also a source. During the last glacial period, there may have been a longer residence time of the Siberian and Canadian high-pressure cells, along with a strengthened Aleutian low-pressure cell. This would have generated regional-scale northeasterly winds and explains derivation of loess from the Yukon River. However, superim-posed upon this synoptic-scale circulation, there may have been strong, southerly katabatic winds from expanded glaciers on the northern flank of the Alaska Range. These winds could have provided eolian silt from the Tanana River. Yukon River and Tanana River sediments are highly calcareous, whereas Fairbanks-area loess is not. This suggests that carbonate leaching in loess kept ahead of sedimentation and that late Quaternary loess in central Alaska was deposited relatively slowly. ?? 2006 NRC Canada.

  7. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this spectacular MODIS image from November 7, 2001, the skies are clear over Alaska, revealing winter's advance. Perhaps the most interesting feature of the image is in its center; in blue against the rugged white backdrop of the Alaska Range, Denali, or Mt. McKinley, casts its massive shadow in the fading daylight. At 20,322 ft (6,194m), Denali is the highest point in North America. South of Denali, Cook Inlet appears flooded with sediment, turning the waters a muddy brown. To the east, where the Chugach Mountains meet the Gulf of Alaska, and to the west, across the Aleutian Range of the Alaska Peninsula, the bright blue and green swirls indicate populations of microscopic marine plants called phytoplankton. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  8. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this spectacular MODIS image from November 7, 2001, the skies are clear over Alaska, revealing winter's advance. Perhaps the most interesting feature of the image is in its center; in blue against the rugged white backdrop of the Alaska Range, Denali, or Mt. McKinley, casts its massive shadow in the fading daylight. At 20,322 ft (6,194m), Denali is the highest point in North America. South of Denali, Cook Inlet appears flooded with sediment, turning the waters a muddy brown. To the east, where the Chugach Mountains meet the Gulf of Alaska, and to the west, across the Aleutian Range of the Alaska Peninsula, the bright blue and green swirls indicate populations of microscopic marine plants called phytoplankton.

  9. Deep-seated gravitational slope deformations near the Trans-Alaska Pipeline, east-central Alaska Range, Alaska, USA

    NASA Astrophysics Data System (ADS)

    Newman, S. D.; Clague, J. J.; Rabus, B.; Stead, D.

    2013-12-01

    Multiple, active, deep-seated gravitational slope deformations (DSGSD) are present near the Trans-Alaska Pipeline and Richardson Highway in the east-central Alaska Range, Alaska, USA. We documented spatial and temporal variations in rates of surface movement of the DSGSDs between 2003 and 2011 using RADARSAT-1 and RADARSAT-2 D-InSAR images. Deformation rates exceed 10 cm/month over very large areas (>1 km2) of many rock slopes. Recent climatic change and strong seismic shaking, especially during the 2002 M 7.9 Denali Fault earthquake, appear to have exacerbated slope deformation. We also mapped DSGSD geological and morphological characteristics using field- and GIS-based methods, and constructed a conceptual 2D distinct-element numerical model of one of the DSGSDs. Preliminary results indicate that large-scale buckling or kink-band slumping may be occurring. The DSGSDs are capable of generating long-runout landslides that might impact the Trans-Alaska Pipeline and Richardson Highway. They could also block tributary valleys, thereby impounding lakes that might drain suddenly. Wrapped 24-day RADARSAT-2 descending spotlight interferogram showing deformation north of Fels Glacier. The interferogram is partially transparent and is overlaid on a 2009 WorldView-1 panchromatic image. Acquisition interval: August 2 - August 26, 2011. UTM Zone 6N.

  10. Traces of Old Glaciations in East-central Alaska

    NASA Astrophysics Data System (ADS)

    Duk-Rodkin, A.; Barendregt, R. W.; Weber, F.

    2001-12-01

    The East-central Alaska record of glaciations is similar to that preserved in the west-central Yukon. Surficial geologic mapping of the Yukon-Tanana upland has indicated at least 5 glacial periods including at least one early Holocene. The two earliest glaciations are of pre-Mid Pleistocene age and followed regional erosion and renewed uplift ca.4 Ma. The earliest glaciation of west-central Yukon occurred between 2.6 and 2.9 Ma, forming a continuous carapace of ice covering all the mountain ranges except for a small part of the Dawson Range. This first glaciation was also the most extensive in the region, and resulted in the NW diversion of Yukon River into Alaska by the Cordilleran Ice Sheet. Stratigraphic evidence of 6 glaciations of pre-Mid Pleistocene age is preserved in the western Canadian sector of the Tintina Trench. The limits of these glaciations have been mapped in Yukon on the basis of glacial landforms and the distribution of erratics. Although morphological features of older glaciations (Plio-Pleistocene) are generally not well preserved, there is relatively good control on the distribution of glacial features for two of the older glaciations in Mt.Harper, Alaska. Stratigraphic evidence of at least 3 older glaciations is found in the Goodpastor River. An initial magnetostratigraphic study of three sites in east-central Alaska have yielded normal magnetic polarities only. The sites are:(1) a relatively weathered lowermost till outcropping along Goodpastor River on the Yukon-Tanana upland,(2) an extremely weathered high level moraine (609m) on the western side of the Gerstle River, near Granite Mt.in the Alaska Range and (3)ca.914m pediment containing glacial erratics and a luvisol at its surface, located on Tok River, Tanana Valley, Alaska Range. The normal polarity of the first site likely indicates a Brunhes age rather than a normal subchron within the Matuyama Reversed Chron based on the modest degree of weathering of the till and lack of any

  11. 75 FR 38452 - Fisheries of the Exclusive Economic Zone Off Alaska; Central Gulf of Alaska License Limitation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-02

    ... October 1, 1998 (63 FR 52642), and the LLP was implemented on January 1, 2000. The LLP for groundfish... Economic Zone Off Alaska; Central Gulf of Alaska License Limitation Program; Amendment 86 AGENCY: National... endorsement on licenses issued under the license limitation program (LLP) if those licenses have been used...

  12. 77 FR 50389 - Fisheries of the Exclusive Economic Zone Off Alaska; “Other Rockfish” in the Central Regulatory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-21

    ... Economic Zone Off Alaska; ``Other Rockfish'' in the Central Regulatory Area of the Gulf of Alaska AGENCY... Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2012 total... Groundfish of the Gulf of Alaska (FMP) prepared by the North Pacific Fishery Management Council...

  13. Petrology of the Plutonic Rocks of west-central Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    1970-01-01

    A series of plutons in west-central Alaska defines the Hogatza plutonic belt which extends for about 200 miles in an east-west direction from the northeastern Seward Peninsula to the Koyukuk River. The plutonic rocks have an aggregate area of about 1,200 square miles and their composition, distribution, and possible petrogenesis are discussed for the first time in this report. Field, petrographic and chemical data supported by K/Ar age dating indicate the plutonic rocks are divisible into two suites differing in age, location, and composition. The western plutons are mid-Cretaceous (~100 m.y.) in age and consist of a heterogeneous assemblage of monzonite, syenite, quartz monzonite. Associated with these granitic rocks is a group of alkaline sub-silicic rocks that forma belt of intrusive complexes extending for a distance of at least 180 miles from west-central Alaska to the Bering Sea. The complex at Granite Mountain shows a rare example of zoning from an alkaline rim to a quartz-bearing core. The occurrence of a similar complex at Cape Dezhnev on the easternmost tip of Siberia suggests the alkaline province may extend into Siberia. The easternmost plutons are Late Cretaceous (180 m.y.) in age and composed primarily of granodiorite and quartz monzonite similar to calc-alkaline plutons found throughout the North America Cordillera. The plutons are epizonal and intrude deformed but unmetamorphosed Lower Cretaceous andesitic volcanics and volcanic graywacke which constitute the highly mobile Yukon-Koyukuk volcanogenic province of west-central Alaska. No older rocks have been found within the confines of this vast tract; the occurrence of a bounding ophiolite sequence has lead to the suggestion that the province was formed by large-scale rifting and is underlain by oceanic crust. The possibility of no juvenile sialic crust over much of the area suggests that the potassium-rich magma now represented by the alkaline rocks originated in the mantle. The distribution of the

  14. Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

    NASA Astrophysics Data System (ADS)

    Tsushima, A.; Matoba, S.; Shiraiwa, T.; Okamoto, S.; Sasaki, H.; Solie, D. J.; Yoshikawa, K.

    2014-04-01

    A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m-depth temperature in the borehole was -2.2 °C, which corresponded to annual mean air temperature at the drilling site. In this ice core, there were many melt-refrozen layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m w.eq. to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ±3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 1.88 m w.eq per year. Our results suggest that temporal variation in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

  15. Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

    NASA Astrophysics Data System (ADS)

    Tsushima, A.; Matoba, S.; Shiraiwa, T.; Okamoto, S.; Sasaki, H.; Solie, D. J.; Yoshikawa, K.

    2015-02-01

    A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m depth temperature in the borehole was -2.2 °C, which corresponded to the annual mean air temperature at the drilling site. In this ice core, there were many melt-refreeze layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ± 3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 2.04 m w.eq. yr-1. Our results suggest that temporal variations in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

  16. South Central California Coastline and Channel Islands

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This distant and very oblique image of the south Central California Coastline and Channel Islands (35.0N, 119.0W) offers a spectacular and scenic view of the southern west coast, the central San Joaquin Valley, the entire Sierra Nevada Range and across the southwest to the Rocky Mountains on the horizon.

  17. Character, distribution, and tectonic significance of accretionary terranes in the Central Alaska Range

    NASA Astrophysics Data System (ADS)

    Jones, David L.; Silberling, N. J.; Gilbert, Wyatt; Coney, Peter

    1982-05-01

    The central part of the Alaska Range near Mount McKinley is composed of nine separate tectonostratigraphic terranes that were accreted in southern Alaska during late Mesozoic time. These terranes now form long, linear, fault-bounded belts that are subparallel to the Denali fault on the north but oblique to the fault on the south. The postaccretion right lateral offset along the Denali fault system is about 200 km. From north to south the major terranes are (1) Yukon-Tanana terrane, metasedimentary and metavolcanic rocks, mostly undated, but including rocks of known late Paleozoic age; polymetamorphosed with terminal events in late Mesozoic, (2) Pingston terrane, isoclinally folded Upper Triassic deep-water silty limestone, quartzite, and carbonaceous slate, folded with upper Paleozoic phyllite, chert, tuff, and minor limestone, (3) McKinley terrane, upper Paleozoic flysch, chert, and minor limestone, intruded by large gabbro sills and dikes and overlain by thick piles of Triassic porphyritic pillow lava; the top of the section is thick sequence of upper Mesozoic conglomerate, flysch, chert, and phyllite, (4) Dillinger terrane, very thick sequence of strongly folded lower Paleozoic micaceous sandstone (turbidites), graptolitic shale, and deep-water limestone, locally overlain unconformably by Jurassic fossiliferous sandstone or Triassic (?) pillow basalt, (5) Windy terrane, heterogeneous assemblage of serpentinite, basalt, tuff, and chert (= ophiolite?) with Paleozoic and Mesozoic flysch and blocks of mid-Paleozoic fossiliferous limestone, (6) Mystic terrane, predominantly upper Paleozoic flysch and conglomerate, but also includes lower Paleozoic graptolitic shale, pillow basalt, and shallow-water limestone, and upper Paleozoic fossiliferous limestone, sandstone, chert, and undated pillow basalt, (7) Chulitna terrane, Upper Devonian ophiolite overlain by upper Paleozoic chert, volcanic conglomerate, limestone, and flysch, capped by Lower Triassic limestone and Upper

  18. Block rotation in east-central Alaska: a framework for evaluating earthquake potential?

    USGS Publications Warehouse

    Page, R.A.; Plafker, G.; Pulpan, H.

    1995-01-01

    Geologic and seismic data reveal a set of parallel, active, strike-slip faults in east-central Alaska between the Denali and Tintina fault systems. The faults strike northeast to north-northeast, at a high angle to the bounding dextral fault systems, and exhibit sinistral slip. This hypothesizes that this set of faults divides the crust into long blocks that are rotating clockwise in response to northerly compression resulting from Pacific-North American plate convergence. It is suggested that these faults have produced most of the large historical earthquakes in east-central Alaska between the Alaska Range and the Yukon River. -Authors

  19. Floods of August 1967 in east-central Alaska

    USGS Publications Warehouse

    Childers, Joseph M.; Meckel, James P.; Anderson, Gary S.

    1972-01-01

    East-central Alaska had record floods near Fairbanks following extensive rains of August 8-20, 1967. Precipitation during this period totaled as much as 10 inches, which is close to the average annual precipitation for this area. The most extensive flooding occurred in the White Mountains northeast of Fairbanks and along the major streams draining those mountains. Some of the major streams flooded were the Salcha, Chena, Chatanika, Tolovana, and lower Tanana Rivers, and Birch Creek west of Circle. Peak discharges on some streams in the flood area were from two to four times the probable 50-year flood. The peak discharge of 74,400 cubic feet per second of the Chena River at Fairbanks, from 1,980 square miles of drainage area, was 2.6 times the 50-year flood. The rise of ground-water levels in the Tanana River flood plain to the land surface during the flood caused foundation failures and prevented drainage of subsurface structures. Above-normal ground-water levels existed until the middle of September. Total flood damage was estimated in excess of $85 million. Six lives were reported lost, and about 12,000 persons were evacuated during the flood. This report has been prepared to furnish hydrologic data for development planning. Included are discussions of antecedent streamflow, meteorology of the storm, descriptions of floods, flood damage, flood frequency, ground-water conditions, and stages and discharges of major streams for August 1967.

  20. 78 FR 14076 - Fisheries of the Exclusive Economic Zone Off Alaska; Groundfish of the Gulf of Alaska; Central...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-04

    ...NMFS publishes the standard ex-vessel prices and fee percentage for cost recovery under the Central Gulf of Alaska Rockfish Program. This action is intended to provide participants in a rockfish cooperative with the standard prices and fee percentage for the 2012 fishing year, which was authorized from May 1 through November 15. The fee percentage is 1.4 percent. The fee liability payments......

  1. Geologic map of the Big Delta B-2 quadrangle, east-central Alaska

    USGS Publications Warehouse

    Day, Warren C.; Aleinikoff, John N.; Roberts, Paul; Smith, Moira; Gamble, Bruce M.; Henning, Mitchell W.; Gough, Larry P.; Morath, Laurie C.

    2003-01-01

    New 1:63,360-scale geologic mapping of the Big Delta B-2 quadrangle provides important data on the structural setting and age of geologic units, as well as on the timing of gold mineralization plutonism within the Yukon-Tanana Upland of east-central Alaska. Gold exploration has remained active throughout the region in response to the discovery of the Pogo gold deposit, which lies within the northwestern part of the quadrangle near the south bank of the Goodpaster River. Geologic mapping and associated geochronological and geochemical studies by the U.S. Geological Survey (USGS) and the Alaska Department of Natural Resources, Division of Mining and Water Management, provide baseline data to help understand the regional geologic framework. Teck Cominco Limited geologists have provided the geologic mapping for the area that overlies the Pogo gold deposit as well as logistical support, which has lead to a much improved and informative product. The Yukon-Tanana Upland lies within the Tintina province in Alaska and consists of Paleozoic and possibly older(?) supracrustal rocks intruded by Paleozoic (Devonian to Mississippian) and Cretaceous plutons. The oldest rocks in the Big Delta B-2 quadrangle are Paleozoic gneisses of both plutonic and sedimentary origin. Paleozoic deformation, potentially associated with plutonism, was obscured by intense Mesozoic deformation and metamorphism. At least some of the rocks in the quadrangle underwent tectonism during the Middle Jurassic (about 188 Ma), and were subsequently deformed in an Early Cretaceous contractional event between about 130 and 116 Ma. New U-Pb SHRIMP data presented here on zircons from the Paleozoic biotite gneisses record inherited cores that range from 363 Ma to about 2,130 Ma and have rims of euhedral Early Cretaceous metamorphic overgrowths (116 +/- 4 Ma), interpreted to record recrystallization during Cretaceous west-northwest-directed thrusting and folding. U-Pb SHRIMP dating of monazite from a Paleozoic

  2. OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, SHOWING SECTION MARKER AT BASE OF TREE. VIEW TO SOUTH. - Baton Rouge National Cemetery, 220 North 19th Street, Baton Rouge, East Baton Rouge Parish, LA

  3. OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH PERIMETER FENCE IN BACKGROUND. VIEW TO SOUTH. - Baton Rouge National Cemetery, 220 North 19th Street, Baton Rouge, East Baton Rouge Parish, LA

  4. 7. INTERIOR, KITCHEN SOUTH OF CENTRAL EASTWEST CORRIDOR, FROM ENTRY, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. INTERIOR, KITCHEN SOUTH OF CENTRAL EAST-WEST CORRIDOR, FROM ENTRY, LOOKING SOUTH. - Oakland Naval Supply Center, Administration Building-Dental Annex-Dispensary, Between E & F Streets, East of Third Street, Oakland, Alameda County, CA

  5. 8. VIEW LOOKING SOUTH, SHOWING NORTH ENTRANCE HOUSE AND CENTRAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW LOOKING SOUTH, SHOWING NORTH ENTRANCE HOUSE AND CENTRAL PAVILION, WITH SOUTH ENTRANCE HOUSE AND ENGINE HOUSE BEYOND - Fairmount Waterworks, East bank of Schuylkill River, Aquarium Drive, Philadelphia, Philadelphia County, PA

  6. Break-up characteristics of the Chena River watershed, central Alaska

    NASA Technical Reports Server (NTRS)

    Carlson, R. F. (Principal Investigator); Wendler, G.; Kane, D. L.

    1973-01-01

    The author has identified the following significant results. The snow melt for a small watershed (5130 sq km) in Central Alaska was successfully monitored with ERTS-1 imagery. Aerial photography was used as supporting data for periods without satellite coverage. Comparison both with actual measurements and with a computer model showed good agreement.

  7. Radioactivity at the Copper Creek copper lode prospect, Eagle district, east-central Alaska

    USGS Publications Warehouse

    Wedow, Helmuth; Tolbert, Gene Edward

    1952-01-01

    Investigation of radioactivity anomalies at the Copper Creek copper lode prospect, Eagle district, east-central Alaska, during 1949 disclosed that the radioactivity is associated with copper mineralization in highly metamorphosed sedimentary rocks. These rocks are a roof pendant in the Mesozoic "Charley River" batholith. The radioactivity is probably all due to uranium associated with bornite and malachite.

  8. 29. INTERIOR VIEW OF FERRY MOUSE, SOUTH CENTRAL BUILDING, FIRST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. INTERIOR VIEW OF FERRY MOUSE, SOUTH CENTRAL BUILDING, FIRST LEVEL, LOOKING WEST, FERRYMEN'S QUARTERS - Central Railroad of New Jersey, Jersey City Ferry Terminal, Johnson Avenue at Hudson River, Jersey City, Hudson County, NJ

  9. Tertiary tectonics of the Border Ranges Fault system, north-central Chugach Mountains, Alaska: Sedimentation, deformation and uplift along the inboard edge of a subduction complex

    SciTech Connect

    Little, T.A.

    1988-01-01

    In south-central Alaska the Border Ranges Fault system (BRFS) separates lower Paleogene rocks of a forearc basin sequence from a Cretaceous subduction complex. In a north-central part of the Chugach Mountains the upper Paleocene-lower Eocene Chickaloon Formation was deposited along the seaward margin of the forearc basin as an alluvial fan complex. A field study combining geologic mapping of a {approximately}200 km{sup 2} region, stratigraphic studies, K-Ar and fission-track geochronology, metamorphic petrology, and detailed structural analysis of deformed rocks on both sides of the BRFS has been used to reconstruct the Tertiary history of displacements and uplift events along the inboard edge of Alaska's subduction-accretion complex.

  10. 150,000 years of loess accumulation in central Alaska

    NASA Astrophysics Data System (ADS)

    Jensen, Britta J. L.; Evans, Michael E.; Froese, Duane G.; Kravchinsky, Vadim A.

    2016-03-01

    The Halfway House site in interior Alaska is arguably the most studied loess deposit in northwestern North America. The site contains a complex paleomagnetic and paleoenvironmental record, but has lacked the robust chronologic control that would allow its full potential to be exploited. Detailed reexamination of stratigraphy, paleomagnetics and tephrostratigraphy reveals a relatively complete marine isotope stage (MIS) 6 to Holocene record constrained by the Old Crow (124 ± 10 ka), VT (106 ± 10 ka), Sheep Creek-Klondike (ca. 80 ka), Dominion Creek (77 ± 8 ka) and Dawson (ca. 30.2 cal ka BP) tephras. We show two well-developed paleosols formed during Marine Isotope Stages (MIS) 5e and 5a, while MIS 5c and 5b are either poorly represented or absent. The new tephrostratigraphy presented here is the most complete one to date for the late Pleistocene and indicates MIS 5 sediments are more common than previously recognized. A magnetic excursion within the sediments is identified as the post-Blake excursion (94.1 ± 7.8 ka), providing independent age control and adding to the increasing body of evidence that Alaskan loess is a detailed recorder of variations of the Earth's magnetic field over time. A high-resolution magnetic susceptibility profile placed into this new chronostratigraphic framework supports the hypothesis that wind-intensity is the main variable controlling fluctuations in susceptibility. Correlation of the susceptibility record to global marine δ18O records is complicated by highly variable accumulation rates. We find the lowest rates of accumulation during peak warm and cold stages, while abrupt increases are associated with periods of transition between marine isotope (sub)stages. Building on previous accumulation models for Alaska, surface roughness is likely a leading variable controlling loess accumulation rates during transitions and peak cold periods, but the negligible accumulation during MIS 5e and 5a suggests that loess production was

  11. Structural architecture of the central Brooks Range foothills, Alaska

    USGS Publications Warehouse

    Moore, Thomas E.; Potter, Christopher J.; O'Sullivan, Paul B.

    2002-01-01

    Five structural levels underlie the Brooks Range foothills, from lowest to highest: (1) autochthon, at a depth of ~9 km; (2) Endicott Mountains allochthon (EMA), thickest under the northern Brooks Range (>15 km) and wedging out northward above the autochthon; (3) higher allochthons (HA), with a composite thickness of 1.5+ km, wedging out northward at or beyond the termination of EMA; (4) Aptian-Albian Fortress Mountain Formation (FM), deposited unconformably on deformed EMA and HA and thickening northward into a >7-km-thick succession of deformed turbidites (Torok Formation); (5) gently folded Albian-Cenomanian deltaic deposits (Nanushuk Group). The dominant faulting pattern in levels 2-3 is thin-skinned thrusting and thrust-related folds formed before deposition of Cretaceous strata. These structures are cut by younger steeply south-dipping reverse faults that truncate and juxtapose structural levels 1-4 and expose progressively deeper structural levels to the south. Structural levels 4-5 are juxtaposed along a north-dipping zone of south-vergent folds and thrusts. Stratigraphic and fission-track age data suggest a kinematic model wherein the foothills belt was formed first, by thrusting of HA and EMA as deformational wedges onto the regionally south-dipping authochon at 140-120Ma. After deposition of FM and Torok during mid-Cretaceous hinterland extension and uplift, a second episode of contractional deformation at 60 Ma shortened the older allochthonous deformational wedges (EMA, HA) and overlying strata on north-vergent reverse faults. To the north, where the allochthons wedge out, shortening caused duplexing in the Torok and development of a triangle zone south of the Tuktu escarpment.

  12. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.

  13. Seasonal Variability of South Atlantic Central Water

    NASA Astrophysics Data System (ADS)

    Nobrega Passos, E.; de Freitas Assad, L.; Landau, L.

    2013-05-01

    The South Atlantic Ocean (SAO) is constituted by different density water masses. Among these, the South Atlantic Central Water (SACW) is formed on the Brazil-Falkland Confluence region (BFC) and once formed, it becomes part of the Subtropical Gyre. When approaching again the Brazilian coast, this water mass bifurcates next to São Tomé Cape and part of it flows to the North and part to the South. There is another bifurcation that formed the sub-gyre of the SAO and occurs near 30°S. This work aims to analyze the seasonal variability associated to the SACW trajectory on the SAO basin. To achieve this goal, ECCO2 project's time series of prognostic fields were analysed. The parameters evaluated were temperature, salinity and the zonal and meridional velocity components in averaged monthly fields between January 1992 and November 2010. First a climatological year was calculated and was composed by means from all time series for each month. And second, it was estimate seasonally means for the south hemisphere to summer, autumn, winter and springer. For the analysis, the SACW was separated from the rest of the water masses by isolating it for its temperature, salinity and density index. Then the volume transport (VT) was calculated for seven different sections: A (10°S and 36°W-30°W), B (35°S and 55°W-45°W), C (40°W and 37°S-43°S), D (34°S and 7°E-20°E), E (20°E and 34°S-45°S), F (20°W and 27°S-33°S) and G (10°W and 20°S-25°S). The VT integrated on the water column occupied by SACW was calculated from the zonal and meridional velocities. The analysis showed that the VT balance between the sections is consistent with the climatologic analysis, according to scientific references. The analysis of the climatological VT showed that the VT field integrated in SAWC levels is also consistent with scientific reference. On the seasonal analysis, the sections A and F show a stronger VT during autumn. Since section A is formed from part of the flux of section

  14. Limits to northward drift of the Paleocene Cantwell Formation, central Alaska.

    USGS Publications Warehouse

    Hillhouse, J.W.; Gromme, C.S.

    1982-01-01

    Volcanic rocks of the Paleocene Cantwell Formation in central Alaska apparently originated at a paleolatitude of 83oN (alpha 95 = 9.7o), as indicated by paleomagnetic results. When compared with the Paleocene pole for the North American craton, the 95% confidence limits of the results suggest that terranes N of the Denali fault have moved no more than 550km northward relative to the North American craton since Paleocene time.-Authors

  15. Holocene loess and paleosols in central Alaska: A proxy record of Holocene climate change

    SciTech Connect

    Bigelow, N.H.; Beget, J.E.

    1992-03-01

    Episodic Holocene loess deposition and soil formation in the sediments of the Nenana valley of Central Alaska may reflect Holocene climate change. Periods of loess deposition seem to correlate with times of alpine glacier activity, while paleosols correspond to times of glacial retreat These variations may reflect changes in solar activity Stuiver and Braziunas, 1989. Other mechanisms, such as orbitally forced changes in seasonality, volcanism, and atmospheric C02 variability may also have affected Holocene climates and loess deposition.

  16. OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH LODGE BUILDING AT CENTER BACKGROUND. VIEW TO NORTHWEST. - Baton Rouge National Cemetery, 220 North 19th Street, Baton Rouge, East Baton Rouge Parish, LA

  17. 88. 451 MADISON AVENUE, LIBRARY, SOUTH WALL, WEST CENTRAL SECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. 451 MADISON AVENUE, LIBRARY, SOUTH WALL, WEST CENTRAL SECTION SHOWING WINDOW AND RADIATOR (Pair with NY-5635-89) - Villard Houses, 451-457 Madison Avenue & 24 East Fifty-first Street, New York County, NY

  18. 14. INTERIOR CENTRAL STAIRWAY, FIRST FLOOR LOOKING SOUTH NEWEL POSTS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. INTERIOR CENTRAL STAIRWAY, FIRST FLOOR LOOKING SOUTH NEWEL POSTS WITH LIGHTS - Louisana State Capitol, North Boulevard, Saint Philip, America & Front Streets, Baton Rouge, East Baton Rouge Parish, LA

  19. Central portion of front (south side) from west parking area ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central portion of front (south side) from west parking area - Fitzsimons General Hospital, Main Hospital Building, Charlie Kelly Boulevard, North side, at intersection of Sharon A. Lane Drive, Aurora, Adams County, CO

  20. Central tower of the front ( south side) with the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central tower of the front ( south side) with the top of the porte cochere in the foreground - Fitzsimons General Hospital, Main Hospital Building, Charlie Kelly Boulevard, North side, at intersection of Sharon A. Lane Drive, Aurora, Adams County, CO

  1. PERSPECTIVE VIEW OF CENTRAL BAY OF EAST ARMORY, LOOKING SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PERSPECTIVE VIEW OF CENTRAL BAY OF EAST ARMORY, LOOKING SOUTH SOUTHEAST. - Colt Fire Arms Company, East Armory Building, 36-150 Huyshope Avenue, 17-170 Van Dyke Avenue, 49 Vredendale Avenue, Hartford, Hartford County, CT

  2. 1. Ice Plant, south facade, two central bays. On the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Ice Plant, south facade, two central bays. On the right, the Creamery; to the left, loading dock of Hay and Grain Warehouse. - Curtis Wharf, Ice Plant, O & Second Streets, Anacortes, Skagit County, WA

  3. Interior view, groundfloor passage in central pavilion, looking south. The ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view, ground-floor passage in central pavilion, looking south. The forward opening accesses the elevator shaft. The well articulated doorway behind lets onto a small vestibule located on the west ground floor Verandah of the south wing. - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA

  4. 6. CENTRAL PORTION OF SOUTH SIDE OF BUILDING, FROM PARKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. CENTRAL PORTION OF SOUTH SIDE OF BUILDING, FROM PARKING LOT NORTH OF BERTH B-1 (WESTERN END OF G STREET), LOOKING NORTHEAST, WITH BUILDING 123 AT FAR RIGHT. - Oakland Naval Supply Center, Pier Transit Shed, South of D Street between First & Second Streets, Oakland, Alameda County, CA

  5. Central tower section of the front (south side) with the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central tower section of the front (south side) with the top of the central entrance projection at the bottom - Fitzsimons General Hospital, Main Hospital Building, Charlie Kelly Boulevard, North side, at intersection of Sharon A. Lane Drive, Aurora, Adams County, CO

  6. Ophiolitic terranes of northern and central Alaska and their correlatives in Canada and northeastern Russia

    SciTech Connect

    Patton, W.W. Jr. )

    1993-04-01

    All of the major ophiolitic terranes (Angayucham, Tozitna, Innoko, Seventymile, and Goodnews terranes) in the northern and central Alaska belong to the Tethyan-type' of Moores (1982) and were obducted onto Paleozoic and Proterozoic continental and continental margin terranes in Mesozoic time. Tethyan-type' ophiolitic assemblages also occur in the Slide Mountain terrane in the Canadian Cordillera and extend from western Alaska into northeastern Russia. Although investigators have suggested widely different ages from their times of abduction onto the continent, these ophiolitic terranes display some remarkably similar features: (1) they consist of a stack of imbricated thrust slices dominated by ocean floor sediments, basalt, and high-level gabbro of late Paleozoic and Triassic age; (2) their mafic-ultramafic complexes generally are confined to the uppermost thrust sheets; (3) they lack the large tectonic melanges zones and younger accretionary flysch deposits associated with the ophiolitic terranes of southern Alaska and the Koryak region of northeastern Russia; (4) blueschist mineral assemblages occur in the lower part of these ophiolite terranes and (or) in the underlying continental terranes; and (5) they are bordered on their outboard' side by Mesozoic intraoceanic volcanic arc terranes. Recent geochemical and geologic studies of the mafic-ultramafic complexes in the Anagayucham and Tozitna terranes strongly suggest they were generated in a supra-subduction zone (SSZ) and that they are directly overlain by volcanic rocks of the Koyukuk terrane.

  7. 77 FR 75399 - Fisheries of the Exclusive Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-20

    ...NMFS is prohibiting retention of big skate in the Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2012 total allowable catch of big skate in the Central Regulatory Area of the GOA has been...

  8. 78 FR 27863 - Fisheries of the Exclusive Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-13

    ...NMFS is prohibiting retention of big skate in the Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2013 total allowable catch of big skate in the Central Regulatory Area of the GOA has been...

  9. 75 FR 69601 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Central Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2010 allocation of Pacific ocean perch in this...

  10. 77 FR 39440 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Central Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2012 allocation of Pacific ocean perch in this...

  11. Late Pliocene to late Pleistocene environments preserved at the Palisades Site, central Yukon River, Alaska

    NASA Astrophysics Data System (ADS)

    Matheus, Paul; Begét, James; Mason, Owen; Gelvin-Reymiller, Carol

    2003-07-01

    The Palisades Site is an extensive silt-loam bluff complex on the central Yukon River preserving a nearly continuous record of the last 2 myr. Volcanic ash deposits present include the Old Crow (OCt; 140,000 yr), Sheep Creek (SCt; 190,000 yr), PA (2.02 myr), EC (ca. 2 myr), and Mining Camp (ca. 2 myr) tephras. Two new tephras, PAL and PAU, are geochemically similar to the PA and EC tephras and appear to be comagmatic. The PA tephra occurs in ice-wedge casts and solifluction deposits, marking the oldest occurrence of permafrost in central Alaska. Three buried forest horizons are present in association with dated tephras. The uppermost forest bed occurs immediately above the OCt; the middle forest horizon occurs below the SCt. The lowest forest bed occurs between the EC and the PA tephras, and correlates with the Dawson Cut Forest Bed. Plant taxa in all three peats are common elements of moist taiga forest found in lowlands of central Alaska today. Large mammal fossils are all from common late Pleistocene taxa. Those recovered in situ came from a single horizon radiocarbon dated to ca. 27,000 14C yr B.P. The incongruous small mammal assemblage in that horizon reflects a diverse landscape with both wet and mesic environments.

  12. Neogene transpressional foreland basin development on the north side of the central alaska range, usibelli group and nenana gravel, tanana basin

    USGS Publications Warehouse

    Ridgway, K.D.; Thoms, E.E.; Layer, P.W.; Lesh, M.E.; White, J.M.; Smith, S.V.

    2007-01-01

    Neogene strata of the Tanana basin provide a long-term record of a northwardpropagating, transpressional foreland-basin system related to regional shortening of the central Alaska Range and strike-slip displacement on the Denali fault system. These strata are ???2 km thick and have been deformed and exhumed in thrust faults that form the foothills on the north side of the Alaska Range. The lower part of the sedimentary package, the Usibelli Group, consists of 800 m of mainly Miocene strata that were deposited in fluvial, lacustrine, and peat bog environments of the foredeep depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as recycled Upper Cretaceous palynomorphs, indicate that the Miocene foreland-basin system was supplied increasing amounts of sediment from lithologies currently exposed in thrust sheets located south of the basin. The upper part of the sedimentary package, the Nenana Gravel, consists of 1200 m of mainly Pliocene strata that were deposited in alluvial-fan and braidplain environments in the wedge-top depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as 40Ar/39Ar dating of detrital feldspars in sandstone and from granitic clasts in conglomerate, indicate that lithologies exposed in the central Alaska Range provided most of the detritus to the Pliocene foreland-basin system. 40Ar/39Ar dates from detrital feldspar grains also show that two main suites of plutons contributed sediment to the Nenana Gravel. Detrital feldspars with an average age of 56 Ma are interpreted to have been derived from the McKinley sequence of plutons located south of the Denali fault. Detrital feldspars with an average age of 34 Ma are interpreted to have been derived from plutons located north of the Denali fault. Plutons located south of the Denali fault provided detritus for the lower part of the Nenana Gravel, whereas plutons located north of the Denali fault began to

  13. FY10 RARE Final Report to Region 10: The functional Assessment of Alaska Peatlands in Cook Inlet Basin - report

    EPA Science Inventory

    Peatlands in south central Alaska form the predominant wetland class in the lowlands that encompass Cook Inlet. These peatlands are also in areas of increasing human development in Alaska. Currently Alaska peatlands are extensive and largely pristine. This study focused onobtaini...

  14. Regional Geochemical Results from the Reanalysis of NURE Stream Sediment Samples - Eagle 3? Quadrangle, East-Central Alaska

    USGS Publications Warehouse

    Crock, J.G.; Briggs, P.H.; Gough, L.P.; Wanty, R.B.; Brown, Z.A.

    2007-01-01

    This report presents reconnaissance geochemical data for a cooperative study in the Fortymile Mining District, east-central Alaska, initiated in 1997. This study has been funded by the U.S. Geological Survey (USGS) Mineral Resources Program. Cooperative funds were provided from various State of Alaska sources through the Alaska Department of Natural Resources. Results presented here represent the initial reconnaissance phase for this multidisciplinary cooperative study. In this phase, 239 sediment samples from the Eagle 3? Quadrangle of east-central Alaska, which had been collected and analyzed for the U.S. Department of Energy's National Uranium Resource Evaluation program (NURE) of the 1970's (Hoffman and Buttleman, 1996; Smith, 1997), are reanalyzed by newer analytical methods that are more sensitive, accurate, and precise (Arbogast, 1996; Taggart, 2002). The main objectives for the reanalysis of these samples were to establish lower limits of determination for some elements and to confirm the NURE data as a reliable predictive reconnaissance tool for future studies in Alaska's Eagle 3? Quadrangle. This study has wide implications for using the archived NURE samples and data throughout Alaska for future studies.

  15. Assessment of undiscovered petroleum resources in Central and South America

    USGS Publications Warehouse

    Schenk, C.J.

    2002-01-01

    The USGS has assessed undiscovered conventional oil and gas resources in 128 selected petroleum provinces of the world. Of these 128 provinces, 23 are in South America, Central America, and the Caribbean area. In the USGS 2000 Assessment, the provinces resulted in mean totals for undiscovered resource of 105 billion bbl of oil and 487 tcf of gas. The potential for giant oil and gas fields is greatest in the basins along the Atlantic margin of eastern South America, from the Santos Basin in the south to the Guyana-Suriname Basin in the north. The potential for giant fields is mainly offshore, in water depths up to 3600 m. The South and Central America region ranks third in the world for undiscovered conventional oil and gas behind the Middle East and the Former Soviet Union.

  16. Abundance, trends and distribution of baleen whales off Western Alaska and the central Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Zerbini, Alexandre N.; Waite, Janice M.; Laake, Jeffrey L.; Wade, Paul R.

    2006-11-01

    Large whales were extensively hunted in coastal waters off Alaska, but current distribution, population sizes and trends are poorly known. Line transect surveys were conducted in coastal waters of the Aleutian Islands and the Alaska Peninsula in the summer of 2001-2003. Abundances of three species were estimated by conventional and multiple covariate distance sampling (MCDS) methods. Time series of abundance estimates were used to derive rates of increase for fin whales ( Balaenoptera physalus) and humpback whales ( Megaptera novaeangliae). Fin whales occurred primarily from the Kenai Peninsula to the Shumagin Islands, but were abundant only near the Semidi Islands and Kodiak. Humpback whales were found from the Kenai Peninsula to Umnak Island and were more abundant near Kodiak, the Shumagin Islands and north of Unimak Pass. Minke whales ( B. acutorostrata) occurred primarily in the Aleutian Islands, with a few sightings south of the Alaska Peninsula and near Kodiak Island. Humpback whales were observed in large numbers in their former whaling grounds. In contrast, high densities of fin whales were not observed around the eastern Aleutian Islands, where whaling occurred. Average abundance estimates (95% CI) for fin, humpback and minke whales were 1652 (1142-2389), 2644 (1899-3680), and 1233 (656-2315), respectively. Annual rates of increase were estimated at 4.8% (95% CI=4.1-5.4%) for fin and 6.6% (5.2-8.6%) for humpback whales. This study provides the first estimate of the rate of increase of fin whales in the North Pacific Ocean. The estimated trends are consistent with those of other recovering baleen whales. There were no sightings of blue or North Pacific right whales, indicating the continued depleted status of these species.

  17. Investigation of Genetic Variation Underlying Central Obesity amongst South Asians

    PubMed Central

    Scott, William R.; Zhang, Weihua; Loh, Marie; Tan, Sian-Tsung; Lehne, Benjamin; Afzal, Uzma; Peralta, Juan; Saxena, Richa; Ralhan, Sarju; Wander, Gurpreet S.; Bozaoglu, Kiymet; Sanghera, Dharambir K.; Elliott, Paul; Scott, James; Chambers, John C.; Kooner, Jaspal S.

    2016-01-01

    South Asians are 1/4 of the world’s population and have increased susceptibility to central obesity and related cardiometabolic disease. Knowledge of genetic variants affecting risk of central obesity is largely based on genome-wide association studies of common SNPs in Europeans. To evaluate the contribution of DNA sequence variation to the higher levels of central obesity (defined as waist hip ratio adjusted for body mass index, WHR) among South Asians compared to Europeans we carried out: i) a genome-wide association analysis of >6M genetic variants in 10,318 South Asians with focused analysis of population-specific SNPs; ii) an exome-wide association analysis of ~250K SNPs in protein-coding regions in 2,637 South Asians; iii) a comparison of risk allele frequencies and effect sizes of 48 known WHR SNPs in 12,240 South Asians compared to Europeans. In genome-wide analyses, we found no novel associations between common genetic variants and WHR in South Asians at P<5x10-8; variants showing equivocal association with WHR (P<1x10-5) did not replicate at P<0.05 in an independent cohort of South Asians (N = 1,922) or in published, predominantly European meta-analysis data. In the targeted analyses of 122,391 population-specific SNPs we also found no associations with WHR in South Asians at P<0.05 after multiple testing correction. Exome-wide analyses showed no new associations between genetic variants and WHR in South Asians, either individually at P<1.5x10-6 or grouped by gene locus at P<2.5x10−6. At known WHR loci, risk allele frequencies were not higher in South Asians compared to Europeans (P = 0.77), while effect sizes were unexpectedly smaller in South Asians than Europeans (P<5.0x10-8). Our findings argue against an important contribution for population-specific or cosmopolitan genetic variants underlying the increased risk of central obesity in South Asians compared to Europeans. PMID:27195708

  18. Rhyolitic calderas of the Yukon-Tanana Terrane, east central Alaska: volcanic remnants of a mid-Cretaceous magmatic arc

    USGS Publications Warehouse

    Bacon, C.R.; Foster, H.L.; Smith, James G.

    1990-01-01

    Four large but poorly exposed rhyolitic calderas are present in the Yukon-Tanana terrane (YTT) in east central Alaska. At least two are mid-Cretaceous in age (~93 Ma). Similar volcanic rocks, the South Fork Volcanics, occur northeast of the Tintina fault in Yukon Territory. Evidence for the calderas consists of thick deposits of devitrified crystal- and lithic-rich densely welded tuff, interpreted as caldera fill, associated with lava domes or shallow intrusive rocks. Coeval outflow sheets have been largely stripped by erosion. The calderas are preserved within a northeast trending depression extending across the axis of the elongate mid-Cretaceous plutonic province. Trace element abundances in andesites and rhyolites associated with the caldera structures are similar to those of volcanic and plutonic rocks of subduction-related magmatic arcs developed on continental crust and thus are suggestive of formation in such an environment. Late Cretaceous and early Tertiary igneous rocks in the YTT near the calderas are interpreted to have been emplaced in a more extensional setting when the subduction-related magmatic front was farther oceanward. -Authors

  19. 75 FR 8645 - South Central Idaho Resource Advisory Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-25

    ..., USDA. ACTION: Notice of meeting. SUMMARY: The South Central Idaho RAC will meet in Twin Falls, Idaho... meeting will be held at The Red Lion Canyon Springs Hotel, 1357 Blue Lakes Blvd. North, Twin Falls, Idaho... Road East, Twin Falls, Idaho 83301. Comments may also be sent via e-mail to jathomas@fs.fed.us , or...

  20. ELECTRICAL LINES ARRIVE FROM CENTRAL FACILITIES AREA, SOUTH OF MTR. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ELECTRICAL LINES ARRIVE FROM CENTRAL FACILITIES AREA, SOUTH OF MTR. EXCAVATION RUBBLE IN FOREGROUND. CONTRACTOR CRAFT SHOPS, CRANES, AND OTHER MATERIALS ON SITE. CAMERA FACES EAST, WITH LITTLE BUTTE AND MIDDLE BUTTE IN DISTANCE. INL NEGATIVE NO. 335. Unknown Photographer, 7/1/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  1. 77 FR 48950 - South Central Idaho Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-15

    ...The South Central Idaho Resource Advisory Committee will meet in Jerome, Idaho. The committee is authorized under the Secure Rural Schools and Community Self-Determination Act (Pub. L. 112-141) (the Act) and operates in compliance with the Federal Advisory Committee Act. The purpose of the committee is to improve collaborative relationships and to provide advice and recommendations to the......

  2. 18. SOUTH CENTRAL SECTION OF HISTORIC DISTRICT LOOKING NORTH TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. SOUTH CENTRAL SECTION OF HISTORIC DISTRICT LOOKING NORTH TO WATER TOWER (Buildings No. 43, 42, 78) (Copy negative made from National Archives negative No. 92-F-61B-5) - Fort Sheridan, 25 miles Northeast of Chicago, on Lake Michigan, Lake Forest, Lake County, IL

  3. GENERAL VIEW FROM THE SOUTH, SHOWING CENTRAL COMPLEX WITH THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GENERAL VIEW FROM THE SOUTH, SHOWING CENTRAL COMPLEX WITH THE STOCK BINS FOR RAW MATERIALS IN THE FOREGROUND, FOUR LARGE BOILER UNITS AND STOVE'S AND THE #1 BLAST FURNACE WITH SKIP HOIST IN THE BACKGROUND. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  4. This image, looking due south shows the central part of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    This image, looking due south shows the central part of the north wing of the building, a 2 story facade. In the foreground are several utility chases which span this elevation of the building - Department of Energy, Mound Facility, Electronics Laboratory Building (E Building), One Mound Road, Miamisburg, Montgomery County, OH

  5. 76 FR 14898 - South Central Idaho Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-18

    ...: Notice of meeting. SUMMARY: The South Central Idaho Resource Advisory Committee will meet in Sun Valley... meeting will be held March 30, 2011, 9:30 a.m. ADDRESSES: The meeting will be held at the Sun Valley City Hall Council Chambers, 810 Elkhorn Road, Sun Valley, Idaho 83353. Written comments should be sent...

  6. Introduction: seismology and earthquake engineering in Central and South America.

    USGS Publications Warehouse

    Espinosa, A.F.

    1983-01-01

    Reports the state-of-the-art in seismology and earthquake engineering that is being advanced in Central and South America. Provides basic information on seismological station locations in Latin America and some of the programmes in strong-motion seismology, as well as some of the organizations involved in these activities.-from Author

  7. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure...

  8. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure...

  9. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure 7 to Subpart E of Part 300—Western...

  10. 77 FR 75966 - Control Date for Qualifying Landings History in the Central Gulf of Alaska Trawl Groundfish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ...; 63 FR 52642). Over the course of the past few years, the Council has recommended amendments to the... (77 FR 42629, July 20, 2012). In June 2012, the Council recommended an FMP amendment to reduce halibut... Landings History in the Central Gulf of Alaska Trawl Groundfish Fisheries AGENCY: National Marine...

  11. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Starich, P. J.; Hinze, W. J.; Braile, L. W.

    1985-01-01

    A positive magnetic anomaly, which dominates the MAGSAT scalar field over the south-central United States, results from the superposition of magnetic effects from several geologic sources and tectonic structures in the crust. The highly magnetic basement rocks of this region show good correlation with increased crustal thickness, above average crustal velocity and predominantly negative free-air gravity anomalies, all of which are useful constraints for modeling the magnetic sources. The positive anomaly is composed of two primary elements. The western-most segment is related to middle Proterozoic granite intrusions, rhyolite flows and interspersed metamorphic basement rocks in the Texas panhandle and eastern New Mexico. The anomaly and the magnetic crust are bounded to the west by the north-south striking Rio Grande Rift. The anomaly extends eastward over the Grenville age basement rocks of central Texas, and is terminated to the south and east by the buried extension of the Ouachita System. The northern segment of the anomaly extends eastward across Oklahoma and Arkansas to the Mississippi Embayment. It corresponds to a general positive magnetic region associated with the Wichita Mountains igneous complex in south-central Oklahoma and 1.2 to 1.5 Ga. felsic terrane to the north.

  12. Detrital Zircon Geochronology of Cretaceous and Paleogene Strata Across the South-Central Alaskan Convergent Margin

    USGS Publications Warehouse

    Bradley, Dwight; Haeussler, Peter; O'Sullivan, Paul; Friedman, Rich; Till, Alison; Bradley, Dan; Trop, Jeff

    2009-01-01

    Ages of detrital zircons are reported from ten samples of Lower Cretaceous to Paleogene metasandstones and sandstones from the Chugach Mountains, Talkeetna Mountains, and western Alaska Range of south-central Alaska. Zircon ages are also reported from three igneous clasts from two conglomerates. The results bear on the regional geology, stratigraphy, tectonics, and mineral resource potential of the southern Alaska convergent margin. Chugach Mountains - The first detrital zircon data are reported here from the two main components of the Chugach accretionary complex - the inboard McHugh Complex and the outboard Valdez Group. Detrital zircons from sandstone and two conglomerate clasts of diorite were dated from the McHugh Complex near Anchorage. This now stands as the youngest known part of the McHugh Complex, with an inferred Turonian (Late Cretaceous) depositional age no older than 91-93 Ma. The zircon population has probability density peaks at 93 and 104 Ma and a smattering of Early Cretaceous and Jurassic grains, with nothing older than 191 Ma. The two diorite clasts yielded Jurassic U-Pb zircon ages of 179 and 181 Ma. Together, these findings suggest a Mesozoic arc as primary zircon source, the closest and most likely candidate being the Wrangellia composite terrane. The detrital zircon sample from the Valdez Group contains zircons as young as 69 and 77 Ma, consistent with the previously assigned Maastrichtian to Campanian (Late Cretaceous) depositional age. The zircon population has peaks at 78, 91, 148, and 163 Ma, minor peaks at 129, 177, 330, and 352 Ma, and no concordant zircons older than Devonian. A granite clast from a Valdez Group conglomerate yielded a Triassic U-Pb zircon age of 221 Ma. Like the McHugh Complex, the Valdez Group appears to have been derived almost entirely from Mesozoic arc sources, but a few Precambrian zircons are also present. Talkeetna Mountains - Detrital zircons ages were obtained from southernmost metasedimentary rocks of the

  13. Central Energy System Modernization at Fort Jackson, South Carolina

    SciTech Connect

    Brown, Daryl R.; Chvala, William D.; Dirks, James A.

    2006-11-29

    An evaluation of technology options was conducted for the central energy systems at Fort Jackson, South Carolina. There were two objectives in conducting this study. From a broader viewpoint, the Army would like to develop a systematic approach to management of its central energy systems and selected Fort Jackson for this ''pilot'' study for a prospective Central Energy System Modernization Program. From a site-specific perspective, the objective was to identify the lowest life-cycle cost energy supply option(s) at Fort Jackson for buildings currently served by central boilers and chillers. This study was co-funded by the Army's Southeast Region and the U.S. Department of Energy's Federal Energy Management Program.

  14. Trends of ice breakup date in south-central Ontario

    NASA Astrophysics Data System (ADS)

    Fu, Congsheng; Yao, Huaxia

    2015-09-01

    Large-scale ice phenology studies have revealed overall patterns of later freeze, earlier breakup, and shorter duration of ice in the Northern Hemisphere. However, there have been few studies regarding the trends, including their spatial patterns, in ice phenology for individual waterbodies on a local or small regional scale, although the coherence of ice phenology has been shown to decline rapidly in the first few hundred kilometers. In this study, we extracted trends, analyzed affecting factors, and investigated relevant spatial patterns for ice breakup date time series at 10 locations with record length ≥90 years in south-central Ontario, Canada. Wavelet methods, including the multiresolution analysis (MRA) method for nonlinear trend extraction and the wavelet coherence (WTC) method for identifying the teleconnections between large-scale climate modes and ice breakup date, are proved to be effective in ice phenology analysis. Using MRA method, the overall trend of ice breakup date time series (1905-1991) varied from earlier ice breakup to later ice breakup, then to earlier breakup again from south to north in south-central Ontario. Ice breakup date is closely correlated with air temperature during certain winter/spring months, as well as the last day with snow on the ground and number of snow-on-ground days. The influences of solar activity and Pacific North American on ice breakup were comparatively uniform across south-central Ontario, while those of El Niño-Southern Oscillation, North Atlantic Oscillation, and Arctic Oscillation on ice phenology changed with distance of 50-100 km in the north-south direction.

  15. South America, Central America, the Caribbean, and Mexico

    SciTech Connect

    Deal, C.

    1981-10-01

    Summaries of oil and gas drillings, well completions, production, exploratory wells, exploration activity and wildcat drilling were given for South America, Central America, the Caribbean, and Mexico. The countries, islands, etc. included Argentina, Bahamas, Barbados, Belize, Bolivia, Brazil, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Jamaica, Leeward and Windward Islands, Mexico, Netherlands Antilles, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, El Salvador, Surinam, Trinidad and Venezuela. 16 figures, 120 tables. (DP)

  16. Hydrology of the Arbuckle Mountains area, south-central Oklahoma

    USGS Publications Warehouse

    Fairchild, Roy W.; Hanson, Ronald L.; Davis, Robert E.

    1990-01-01

    Rocks that make up the Arbuckle-Simpson aquifer crop out over ~500 mi2 in the Arbuckle Mountains province in south-central Oklahoma. The aquifer consists of limestone, dolomite, and sandstone of the Arbuckle and Simpson Groups of Late Cambrian to Middle Ordovician age and is about 5,000-9,000 ft thick. The rocks were subjected to intensive folding and faulting associated with major uplift of the area during Early to Late Pennsylvanian time.

  17. Observations of TEC Depletions in South and Central America

    NASA Astrophysics Data System (ADS)

    Valladares, C. E.; Sheehan, R. E.; Pradipta, R.

    2014-12-01

    TEC values gathered with several networks of GPS receivers, which operated in South and Central America and the Caribbean region between 2010 and 2013, have been used to investigate the characteristics and morphology of TEC depletions that develop at these locations. In South America the TEC depletions are associated with low-latitude plasma bubbles. In Central America and the Caribbean region, we found that TEC depletions that occur during magnetically active conditions (Kp > 5o), persist for very long periods and sometimes remain even during afternoon hours. During quiet magnetic conditions, TEC depletions occur around the June solstice in Central America and during the December solstice in the Southern part of South America. We have also studied possible links between mid-latitude depletions and the formation of plasma bubbles at low latitudes. In addition, TEC measurements from North America have been utilized to determine the poleward extension of the mid-latitude depletions. These depletions do not appear to be related to auroral plasma processes or to storm enhanced densities (SED). We are studying the possibility that their initiation process is associated with the disturbance dynamo or the prompt penetrating electric field that develop during storm conditions.

  18. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false South Central Coast Intrastate Air... Air Quality Control Regions § 81.166 South Central Coast Intrastate Air Quality Control Region. The South Central Coast Intrastate Air Quality Control Region (California) consists of the territorial...

  19. Stratiform zinc-lead mineralization in Nasina assemblage rocks of the Yukon-Tanana Upland in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Bressler, Jason R.; Takaoka, Hidetoshi; Mortensen, James K.; Oliver, Douglas H.; Leventhal, Joel S.; Newberry, Rainer J.; Bundtzen, Thomas K.

    1998-01-01

    The Yukon-Tanana Upland of east-central Alaska and Yukon comprises thrust sheets of ductilely deformed metasedimentary and metaigneous rocks of uncertain age and origin that are overlain by klippen of weakly metamorphosed oceanic rocks of the Seventymile-Slide Mountain terrane, and intruded by post-kinematic Early Jurassic, Cretaceous and Tertiary granitoids. Metamorphosed continental margin strata in the Yukon-Tanana Upland of east-central Alaska are thought to be correlative, on the basis of stratigraphic similarities and sparse Mississippian U-Pb zircon and fossil ages (Mortensen, 1992), with middle Paleozoic metasedimentary and metavolcanic rocks in the eastern Alaska Range and in western and southeastern Yukon. Furthermore, rocks in the northern Yukon-Tanana Upland may correlate across the Tintina fault with unmetamorphosed counterparts in the Selwyn Basin (Murphy and Abbott, 1995). Volcanic-hosted (VMS) and sedimentary exhalative (sedex) massive sulfide occurrences are widely reported for these other areas (green-colored unit of fig. 1) but, as yet, have not been documented in the Alaskan part of the Yukon-Tanana Upland. Recent discoveries of VMS deposits in Devono-Mississippian metavolcanic rocks in the Finlayson Lake area of southeastern Yukon (Hunt, 1997) have increased the potential for finding VMS deposits in rocks of similar lithology and age in the Yukon-Tanana Upland of Alaska. Restoration of 450 km of early Tertiary dextral movement along the Tintina fault juxtaposes these two areas.

  20. Distribution of burrowing owls in east-central South Dakota

    USGS Publications Warehouse

    Shaffer, Jill A; Thiele, Jason P.

    2013-01-01

    Western burrowing owl (Athene cunicularia hypugaea) populations have declined across much of western North America, particularly at the northern and eastern edges of the species’ breeding range (Martell et al. 2001, Murphy et al. 2001, Shyry et al. 2001, Skeel et al. 2001, Klute et al. 2003). In South Dakota, the burrowing owl is a summer resident that historically was relatively common throughout the state, but its range has decreased in recent decades, especially in the eastern half of the state (Whitney et al. 1978, South Dakota Ornithologists’ Union [SDOU] 1991, Peterson 1995). Tallman et al. (2002) described the species as uncommon to locally common in western South Dakota, uncommon in the north-central part of the state, and casual (i.e., not within the species’ normal range, but with 3–10 records in the past 10 years) elsewhere in the eastern half. The burrowing owl is a Species of Greatest Conservation Need (South Dakota Department of Game, Fish and Parks [SDGFP] 2006) and a Level I Priority Species in South Dakota (Bakker 2005).

  1. Combined Ice and Water Balances of Maclure Glacier, California, South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, 1967 Hydrologic Year

    USGS Publications Warehouse

    Tangborn, Wendell V.; Mayo, Lawrence R.; Scully, David R.; Krimmel, Robert M.

    1977-01-01

    Combined ice and water balances were measured in the 1967 hydrologic year (October 1-September 30) on four glaciers in western North America ranging in latitude from 37 deg to 63 deg N. This hydrologic year was characterized by heavier than normal winter precipitation in California and Washington and abnormally dry winter conditions in coastal Alaska. In summer the western conterminous states were abnormally dry and central and southern Alaska experienced very wet conditions. Maclure Glacier (lat 37 deg 45' N., 3,650-m (metres) mean equilibrium line altitude) had an above normal winter balance of 3.46 m and a positive annual balance of 1.05 m (metres of water equivalent). South Cascade Glacier (lat 48 deg 22' N., 1900-m mean equilibrium line altitude) had a winter balance of 3.28 m, slightly above average. Above normal summer ablation resulted in a final annual balance of -0.58 m, slightly more negative than has been the case for the past decade. Wolverine Glacier's (lat 60 deg 24' N., 1,200-m mean equilibrium line altitude) winter balance was 1.17 m, considerably below normal; the annual balance was -2.04 m. Gulkana Glacier (lat 63 deg 15' N., 1,700-m mean equilibrium line altitude) had a winter balance of 1.05 m, approximately normal for this glacier; the final annual balance was -0.30 m.

  2. Evidence for formation of a flexural backarc basin by compression and crustal thickening in the central Alaska peninsula

    SciTech Connect

    Bond, G.C.; Lewis, S.D.; Taber, J.; Steckler, M.S.; Kominz, M.A. )

    1988-12-01

    The North Aleutian Basin is a large, Cenozoic sedimentary basin in the northern part of the central Alaska Peninsula and the southern Bering shelf. The gravity anomaly pattern, the geometry, and the structure of the basin suggest that if formed by downward flexure of the backarc lithosphere. Basin modeling suggests that the flexure was driven by the emplacement of surface and subsurface loads having densities comparable to those of oceanic crust and mantle rocks, at approximately the position of the present-day volcanic arc and forearc. The authors suggest that the inferred loads consist of tectonically thickened mafic crustal materials lying beneath the arc and forearc of the central Alaska Peninsula. The crustal thickening may have occurred within a dominantly transpressional regime resulting from oblique convergence between the North American and Pacific plates during the Cenozoic.

  3. Denali fault slip rates and Holocene-late Pleistocene kinematics of central Alaska

    USGS Publications Warehouse

    Matmon, A.; Schwartz, D.P.; Haeussler, P.J.; Finkel, R.; Lienkaemper, J.J.; Stenner, H.D.; Dawson, T.E.

    2006-01-01

    The Denali fault is the principal intracontinental strike-slip fault accommodating deformation of interior Alaska associated with the Yakutat plate convergence. We obtained the first quantitative late Pleistocene-Holocene slip rates on the Denali fault system from dating offset geomorphic features. Analysis of cosmogenic 10Be concentrations in boulders (n = 27) and sediment (n = 13) collected at seven sites, offset 25-170 m by the Denali and Totschunda faults, gives average ages that range from 2.4 ± 0.3 ka to 17.0 ± 1.8 ka. These offsets and ages yield late Pleistocene-Holocene average slip rates of 9.4 ± 1.6, 12.1 ± 1.7, and 8.4 ± 2.2 mm/yr-1 along the western, central, and eastern Denali fault, respectively, and 6.0 ± 1.2 mm/yr-1 along the Totschunda fault. Our results suggest a westward decrease in the mean Pleistocene-Holocene slip rate. This westward decrease likely results from partitioning of slip from the Denali fault system to thrust faults to the north and west. 2006 Geological Society of America.

  4. Central and South America GPS geodesy - CASA Uno

    NASA Technical Reports Server (NTRS)

    Kellogg, James N.; Dixon, Timothy H.

    1990-01-01

    In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest GPS campaign in the world to date. A total of 43 GPS receivers collected approximately 590 station-days of data in American Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA Uno. Scientific goals of the project include measurements of strain in the northern Andes, subduction rates for the Cocos and Nazca plates beneath Central and South America, and relative motion between the Caribbean plate and South America. A second set of measurements are planned in 1991 and should provide preliminary estimates of crustal deformation and plate motion rates in the region.

  5. Early Miocene mylonitization and detachment faulting, South Mountains, central Arizona

    SciTech Connect

    Reynolds, S.J.; Shafiqullah, M.; Damon, P.E.; DeWitt, E.

    1986-04-01

    The South Mountains of central Arizona are one of the geologically simplest metamorphic core complexes of the North American Cordillera. An early Miocene age of mylonitization is indicated by crosscutting relationships between mylonitic fabric and a composite pluton dated at 22-25 Ma by Rb-Sr, U-Th-Pb, and K-Ar techniques. The kinematic agreement and close temporal association of mylonitization and detachment faulting support models in which the two processes are related to an evolving crustal shear zone that accommodated mid-Tertiary continental extension. 19 references, 3 figures, 2 tables.

  6. Facies comparison of autochthonous and allochthonous Permian and Triassic units, north-central Brooks Range, Alaska

    SciTech Connect

    Adams, K.E.

    1985-04-01

    Eight stratigraphic sections of Permian and Triassic rocks have been studied over a 30 km by 150 km area in the Endicott and Philip Smith Mountains of the central Brooks Range. Six of the sections are located on the Endicott Mountains allochthon, and the remaining two are parautochthonous columns in the Mount Doonerak area. The sections record a facies transition between the autochthonous Sadlerochit Group and Shublik Formation of the northeastern Brooks Range and the characteristically siliceous rocks of the allochthonous Siksikpuk and Otuk formations of the western Brooks Range. Laterally continuous and bioturbated beds of fine-grained sandstone, siltstone, and shale dominantly compose the Permian sequence, whereas the Triassic rocks consist of black shales, thin rhythmically bedded siliceous mudstones, and fossiliferous limestones. When the allochthonous sections are restored to a position south of the Mount Doonerak area, a general shallowing trend from southwest to northwest becomes evident within the reconstructed marine basin. To the south and west, the Permian sediments show a marked increase in silica content, with the occurrence of barite and a corresponding decrease in the thickness of the basal, coarser grained clastics. The Triassic formations also document an increase in silica and the presence of barite to the south and west, while becoming significantly sooty and phosphatic to the north and east. Ongoing petrographic and micropaleontologic studies of the field data will clarify these general paleogeographic relationships.

  7. Geologic Map and Engineering Properties of the Surficial Deposits of the Tok Area, East-Central Alaska

    USGS Publications Warehouse

    Carrara, Paul E.

    2007-01-01

    The Tok area 1:100,000-scale map, through which the Alaska Highway runs, is in east-central Alaska about 160 km west of the Yukon border. The surficial geologic mapping in the map area is in support of the 'Geologic Mapping in support of land, resources, and hazards issues in Alaska' Project of the USGS National Cooperative Geologic Mapping Program. The Tok map area contains parts of three physiographic provinces, the Alaska Range, the Yukon-Tanana Upland, and the Northway-Tanana Lowland. The high, rugged, glaciated landscape of the eastern Alaska Range dominates the southwestern map area. The highest peak, an unnamed summit at the head of Cathedral Rapids Creek No. 2, rises to 2166 m. The gently rolling hills of the Yukon-Tanana Upland, in the northern map area, rise to about 1000 m. The Northway-Tanana Lowland contains the valley of the westerly flowing Tanana River. Elevations along the floor of the lowland generally range between 470 and 520 m. The dominant feature within the map is the Tok fan, which occupies about 20 percent of the map area. This large (450 km2), nearly featureless fan contains a high percentage of volcanic clasts derived from outside the present-day drainage of the Tok River. Because the map area is dominated by various surficial deposits, the map depicts 26 different surficial units consisting of man-made, alluvial, colluvial, eolian, lacustrine, organic, glaciofluvial, glacial, and periglacial deposits. The accompanying table provides information concerning the various units including their properties, characteristics, resource potential, and associated hazards in this area of the upper Tanana valley.

  8. Petroleum source potential and thermal maturity of Cantwell Formation (Paleocene), central Alaska Range: a reconnaissance study

    SciTech Connect

    Stanley, R.G.

    1987-05-01

    The Paleocene Cantwell Formation is a sequence of nonmarine sedimentary and volcanic rocks that is widely distributed in the central Alaska Range and locally is more than 3000 m thick. Mudstones and coals in the Cantwell were deposited in a variety of lacustrine and fluvial overbank environments and are of interest as potential source rocks of petroleum. Thirty-eight samples of mudstone and coal were collected from ten outcrops and analyzed using Rock-Eval pyrolysis, vitrinite reflectance (R/sub 0/), and thermal alteration index (TAI). The results suggest that these rocks may be potential sources of gas and possibly oil. Total organic carbon (TOC) in the samples is relatively high, averaging about 2.8% (range 0.5-14.2%) in the mudstones and about 28.8% (range 5.1-50.2%) in the coals. Plots of hydrogen and oxygen indices (HI and OI) on modified van Krevelen diagrams indicate kerogens of types III and IV. In addition, HI values are generally less than 150 and S2/S3 values are generally less than 3, indicating that these kerogens are gas prone. A few samples exhibit somewhat higher values of HI (up to 170) and S2/S3 (up to 18.6) and therefore may be capable of generating small amounts of oil. Values of T/sub max/ (range 437-537/sup 0/C), median R/sub 0/ (range 0.63-4.28), and TAI (range 2.3.-3.8) show that the thermal maturity of the samples varies from mature to postmature with respect to the oil and gas windows.

  9. New glass sponges (Porifera: Hexactinellida) from deep waters of the central Aleutian Islands, Alaska.

    PubMed

    Reiswig, Henry M; Stone, Robert P

    2013-01-01

    Hexactinellida from deep-water communities of the central Aleutian Islands, Alaska, are described. They were mostly collected by the remotely operated vehicle 'Jason II' from 494–2311 m depths during a 2004 RV 'Roger Revelle' expedition, but one shallow-water species collected with a shrimp trawl from 155 m in the same area is included. The excellent condition of the ROV-collected specimens enabled valuable redescription of some species previously known only from badly damaged specimens. New taxa include one new genus and eight new species in five families. Farreidae consist of two new species, Farrea aleutiana and F. aspondyla. Euretidae consists of only Pinulasma fistulosum n. gen., n. sp. Tretodictyidae include only Tretodictyum amchitkensis n. sp. Euplectellidae consists of only the widespread species Regadrella okinoseana Ijima, reported here over 3,700 km from its closest previously known occurrence. The most diverse family, Rossellidae, consists of Aulosaccus ijimai (Schulze), Aulosaccus schulzei Ijima, Bathydorus sp. (young stage not determinable to species), Caulophacus (Caulophacus) adakensis n. sp., Acanthascus koltuni n. sp., Staurocalyptus psilosus n. sp., Staurocalyptus tylotus n. sp. and Rhabdocalyptus mirabilis Schulze. We present argument for reinstatement of the abolished rossellid subfamily Acanthascinae and return of the subgenera  Staurocalyptus Ijima and Rhabdocalyptus Schulze to their previous generic status. These fauna provides important complexity to the hard substrate communities that likely serve as nursery areas for the young stages of commercially important fish and crab species, refuge from predation for both young and adult stages, and also as a focal source of prey for juvenile and adult stages of those same species. PMID:25325089

  10. Geologic and isostatic map of the Nenana Basin area, central Alaska

    USGS Publications Warehouse

    Frost, G.M.; Barnes, D.F.; Stanley, R.G.

    2002-01-01

    Introduction The Nenana Basin area is a prospective petroleum province in central Alaska, and this geologic and isostatic gravity map is part of a petroleum resource assessment of the area. The geology was compiled from published sources (Chapman and others, 1971, 1975a, 1975b, 1982; Chapman and Yeend, 1981; Csejtey and others, 1986; Jones and others, 1983; Pewe and others, 1966; Reed, 1961; and Weber and others, 1992), as shown on the index map (map sheet). Map units are organized and presented according to the scheme of lithotectonic terranes proposed by Jones and others (1987) and Silberling and Jones (1984); we recognize, however, that this terrane scheme is controversial and likely to be revised in the future. In some cases, we combined certain terranes because we were unable to match the terrane boundaries given by Jones and others (1987) and Silberling and Jones (1984) with specific faults shown on existing geologic maps. Postaccretion cover deposits represent overlap assemblages that depositionally overlie accreted terranes. Plutonic igneous rocks shown on this map include several plutons that are clearly postaccretionary, based on isotopic ages and (or) field relations. It is possible that some of the plutons predate accretion, but this has not been demonstrated. According to Jones and others (1982), the terranes in the area of our map were assembled during late Mesozoic or earliest Cenozoic time. The gravity contours are derived from data used in earlier compilations (Barnes, 1961, 1977; Hackett, 1981; Valin and others, 1991; Frost and Stanley, 1991) that are supplemented by some National Oceanic and Atmospheric Administration data along the Alaska Pipeline level line (W.E. Strange, written commun., 1980). The earlier compilations were used for simple Bouguer maps, prepared primarily by non-digital methods, and are superseded by this map. The present map is the result of digital processing that includes the 1967 Geodetic Reference System, the IGSN-71

  11. Alaska Glaciers and Rivers

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

  12. The 2008 Eruption of Kasatochi Volcano, Central Aleutian Islands, Alaska: Reconnaissance Observations and Preliminary Physical Volcanology

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Schneider, D. J.; Prejean, S. G.

    2008-12-01

    The August 7, 2008 eruption of Kasatochi volcano was the first documented historical eruption of this small (3 x 3 km) island volcano with a 1 km2 lake filled crater in the central Aleutian Islands of Alaska. Reports of previous Kasatochi eruptions are unconfirmed and lacking in detail and little is known about the eruptive history. Three explosively-generated ash plumes reaching altitudes of 15 to 20 km were observed in satellite data and were preceded by some of the most intense seismicity yet recorded by the Alaska Volcano Observatory (AVO) seismic network. Eruptive products on Kasatochi Island observed on August 22 and 23 consist of pumice-bearing, lithic-rich pyroclastic-flow deposits overlain by a 1-2 m thick sequence of fine- grained pyroclastic-surge, and -fall deposits all exposed at the coastline. These deposits completely blanket Kasatochi Island to a depth of many meters. Pyroclastic flows entered the sea and extended the coastline 300-400 m beyond prominent wave cut cliffs and sea stacks. Tide gauge data from Adak Island, 80 km to the west, indicate a small tsunami with maximum water amplitude of 20 cm, was initiated during the eruption. Kasatochi volcano lacks a real-time seismic monitoring network. Seismic activity was detected by AVO instruments on Great Sitkin Island 40 km to the west, and thus the timing of eruptive events is approximate. The eruption began explosively at 2201 UTC on August 7, and was followed by at least two additional strong eruptive bursts at 0150 UTC and 0435 UTC, August 8. Satellite data show a significant ash cloud associated with the 0435 UTC event followed by at least 14 hours of continuous ash emission. The lack of a strong ash signature in satellite data suggest that the first two plumes were ash poor. Satellite data also show a large emission of SO2 that entered the stratosphere. Correlation of eruptive periods with deposits on the island is not yet possible, but it appears that pyroclastic flows were emplaced during

  13. Wind energy resource atlas. Volume 7. The south central region

    SciTech Connect

    Edwards, R.L.; Graves, L.F.; Sprankle, A.C.; Elliott, D.L.; Barchet, W.R.; George, R.L.

    1981-03-01

    This atlas of the south central region combines seven collections of wind resource data: one for the region, and one for each of the six states (Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas). At the state level, features of the climate, topography, and wind resource are discussed in greater detail than that provided in the regional discussion, and the data locations on which the assessment is based are mapped. Variations, over several time scales, in the wind resource at selected stations in each state are shown on graphs of monthly average and interannual wind speed and power, and hourly average wind speed for each season. Other graphs present speed, direction, and duration frequencies of the wind at these locations.

  14. Natural phenomena hazards, Hanford Site, south central Washington

    SciTech Connect

    Tallman, A.M.

    1996-04-16

    This document presents the natural phenomena hazard (NPH) loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, at the Hanford Site in south-central Washington State. The purpose of this document is twofold: (1) summarize the NPH that are important to the design and evaluation of structures, systems, and components at the Hanford Site; (2) develop the appropriate natural phenomena loads for use in the implementation of DOE Order 5480.28. The supporting standards, DOE-STD-1020-94, Natural Phenomena Hazards Design and Evaluation Criteria for Department of Energy Facilities (DOE 1994a); DOE-STD-1022-94, Natural Phenomena Hazards Site Characteristics Criteria (DOE 1994b); and DOE-STD-1023-95, Natural Phenomena Hazards Assessment Criteria (DOE 1995) are the basis for developing the NPH loads.

  15. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Hinze, W. J.; Braile, L. W. (Principal Investigator); Starich, P. J.

    1984-01-01

    The South-Central United States Magnetic Anomaly is the most prominent positive feature in the MAGSAT scalar magnetic field over North America. The anomaly correlates with increased crustal thickness, above average crustal velocity, negative free air gravity anomalies and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced to pole and derivative maps provide constraints for a crustal magnetic model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient magnetization or volume to produce the anomaly, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched magnetic material deep in the crust.

  16. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Starich, P. J.

    1985-01-01

    The South-Central United States Magnetic Anomaly is the most prominent positive feature in the MAGSAT scalar magnetic field over North America. The anomaly correlates with increased crustal thickness, above average crustal velocity, negative free-air gravity anomalies and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced-to-pole and derivative maps provide additional constraints for a crustal magnetic model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient magnetization or volume to produce the anomaly, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched magnetic material deep in the crust.

  17. Global GIS database; digital atlas of Central and South America

    USGS Publications Warehouse

    Hearn,, Paul P., Jr.; Hare, T.; Schruben, P.; Sherrill, D.; LaMar, C.; Tsushima, P.

    2000-01-01

    This CD-ROM contains a digital atlas of the countries of Central and South America. This atlas is part of a global database compiled from USGS and other data sources at the nominal scale of 1:1 million and is intended to be used as a regional-scale reference and analytical tool by government officials, researchers, the private sector, and the general public. The atlas includes free GIS software or may also be used with ESRI's ArcView software. Customized ArcView tools, specifically designed to make the atlas easier to use, are also included. The atlas contains the following datasets: country political boundaries, digital shaded relief map, elevation, slope, hydrology, locations of cities and towns, airfields, roads, railroads, utility lines, population density, geology, ecological regions, historical seismicity, volcanoes, ore deposits, oil and gas fields, climate data, landcover, vegetation index, and lights at night.

  18. Biogeochemical characterization of an undisturbed highly acidic, metal-rich bryophyte habitat, east-central Alaska, U.S.A.

    USGS Publications Warehouse

    Gough, L.P.; Eppinger, R.G.; Briggs, P.H.; Giles, S.

    2006-01-01

    We report on the geochemistry of soil and bryophyte-laden sediment and on the biogeochemistry of willows growing in an undisturbed volcanogenic massive sulfide deposit in the Alaska Range ecoregion of east-central Alaska. We also describe an unusual bryophyte assemblage found growing in the acidic metal-rich waters that drain the area. Ferricrete-cemented silty alluvial sediments within seeps and streams are covered with the liverwort Gymnocolea inflata whereas the mosses Polytrichum commune and P. juniperinum inhabit the area adjacent to the water and within the splash zone. Both the liverwort-encrusted sediment and Polytrichum thalli have high concentrations of major and trace metal cations (e.g., Al, As, Cu, Fe, Hg, La, Mn, Pb, and Zn). Soils in the area do not reflect the geochemical signature of the mineral deposit and we postulate they are influenced by the chemistry of eolian sediments derived from outside the deposit area. The willow, Salix pulchra, growing mostly within and adjacent to the larger streams, has much higher concentrations of Al, As, Cd, Cr, Fe, La, Pb, and Zn when compared to the same species collected in non-mineralized areas of Alaska. The Cd levels are especially high and are shown to exceed, by an order of magnitude, levels demonstrated to be toxic to ptarmigan in Colorado. Willow, growing in this naturally occurring metal-rich Red Mountain alteration zone, may adversely affect the health of browsing animals. ?? 2006 Regents of the University of Colorado.

  19. Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

    USGS Publications Warehouse

    Ball, Lyndsay B.; Smith, Bruce D.; Minsley, Burke J.; Abraham, Jared D.; Voss, Clifford I.; Astley, Beth N.; Deszcz-Pan, Maria; Cannia, James C.

    2011-01-01

    In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

  20. The crustal structure of south central Mongolia using receiver functions

    NASA Astrophysics Data System (ADS)

    He, Jing; Wu, Qingju; Sandvol, Eric; Ni, James; Gallegos, Andrea; Gao, Mengtan; Ulziibat, Munkhuu; Demberel, Sodnomsambuu

    2016-06-01

    The crustal thickness H and average crustal velocity ratio k (Vp/Vs) beneath south central Mongolia are investigated using the H-k stacking method based on teleseismic radial receiver functions. Our primary results reveal that the local crustal thickness varies from 38 to 46 km with an average value of 43 km. Thicker crust is found beneath the western Hentey Mountains, while thinner crust is located in the southern area of the Zuunbayan fault zone. The Bouguer gravity anomalies exhibit a strong correlation with the overall crustal thickness pattern throughout most of our study regime. Moreover, a new approach which integrates the Bouguer anomaly gradient and the receiver function-derived crustal thickness is adopted to calculate the density of the lower crust underneath central Mongolia. Fairly dense lower crust of approximately 3000 kg/m3 is found in the Middle Gobi Desert. The measured crustal Vp/Vs ratio ranges from 1.68 to 1.83 with an average value of 1.74. Low Vp/Vs ratio is found beneath the western Hentey Mountains. In general, low Vp/Vs ratios correlate well with regions of quartz-rich crust and high heat flow. High Vp/Vs ratios occur in the Middle Gobi volcanic regions and the Mesozoic Southern Gobi Basin.

  1. The diorite at West Warren, south-central Massachusetts

    USGS Publications Warehouse

    Pomeroy, John S.

    1974-01-01

    Follated, syntectonic, concordant intrusive bodies of mostly diorite and meladiorite with less abundant quartz diorite and norite have been mapped in the West Warren area of south-central Massachusetts. The rocks of the pluton range from a medium colored phase of diorite and quartz diorite to a dark colored phase of meladiorite and norite. Major minerals In the dioritic rocks are calcic andesine, green hornblende, brown biotite, and hypersthene. Igneous textures are dominant, and retrograde or deuteric effects are generally minor. Silica and alumina contents of the dioritic rocks are somewhat higher than for average diorites; conversely, the oxides of iron, magnesium, and calcium are generally lower. Normative quartz, albite, and anorthite are higher and orthoclase is lower in the samples than In the average diorite. Sizeable plutons of diorite-norite are uncommon in central Massachusetts. The West Warren body, roughly 26 km2 (10 square miles) in area, bears little petrochemical relation to adjacent rock units. The pluton can be construed as belonging to a belt of intrusive mafic rocks which stretches from southeastern New York to coastal Maine.

  2. The Middle Fork Plutonic Complex: A plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range

    SciTech Connect

    Solie, D.N.

    1988-01-01

    The 57 m.y. Middle Fork Plutonic Complex (MFPC) intrudes Paleozoic metasedimentary rocks south of the Farewell Fault zone in the north-central Alaska Range. Though spatially related to the late Cretaceous - Early Tertiary subduction-related Alaska Range batholith, MFPC is more characteristic of an extensional or anorogenic setting. A swarm of basalt, hawaiite and rhyolite dikes east of the complex intruded, and was intruded by, the plutonic rocks. Approximately 30% of the exposed rock in the 125 km[sup 2] complex is hedenbergite - fayalite syenite, [approx equal]20% is peralkalin arfvedsonite-biotite alkali-feldspar granite (AF granite), and [le]20% is pyroxene-olivine-biotite gabbro. The rest is a mixed unit including clinopyroxene-biotite-amphibole diorite, and hornblende-biotite granite (HB granite). K-Ar and Rb-Sr radiometric dating of rock types shows that they are coeval. Their close spatial and temporal relationships led to complex magmatic interactions. Calculated initial [sup 87]Sr/[sup 86]Sr for gabbro and diorite group is around 0.705 to 0.706. HB granites are heterogeneous, but fall mostly around 0.707 to 0.708. Hypersolvus syenites and AF granites form an isochron with initial [sup 87]Sr/[sup 86]Sr of 0.70965. These groupings suggest that at least three different magmas formed the MFPC; scatter of isotopic data reflects mutual contamination and assimilation. Consanguinous hypersolvus syenite and AF granite mineralogy appears to be controlled by fluorine in the magma chamber. Eruptive stratigraphy, as predicted by intrusive history of MFPC, compares favorably with volcanic stratigraphies of peralkaline volcanic systems worldwide, and MFPC may be modelled as the root zone of a peralkaline volcanic system.

  3. Basement involvement in the south-central Taiwan thrust belt

    NASA Astrophysics Data System (ADS)

    Brown, Dennis; Camanni, Giovanni; Alvarez, Joaquina; Ayala, Concepcion; Wu, Yih-Min; Hsieh, Hsien-Hsiang

    2015-04-01

    The Taiwan mountain belt is generally thought to develop above a shallow, through-going basal detachment confined to within the sedimentary cover of the Eurasian continental margin. Recently acquired surface geology, when combined with seismic tomography, earthquake hypocenter, and gravity data suggest, however, that basement is also involved in the deformation in south-central Taiwan. Since basement does not crop out in south central Taiwan, we adopt a P-wave velocity of 5.2 km/s has a proxy for the basement-cover interface and use it as a reference horizon. This interpretation is then tested as a density contrast by 3D modeling of the Bouguer anomaly data. The good fit between the two suggests that this surface provides a reasonable proxy as an interpretation for the top of the basement in what follows. The data suggests that, in the west, beneath the Coastal Plain and the Western Foothills, the mountain belt is evolving above a southward deepening level of detachment that is illuminated by sub-horizontal clusters of earthquake hypocenters located near the basement-cover interface. In much of the study area, this detachment appears to be below the depth of the basal thrust determined from geological constraints provided by the thrust system mapped at the surface. Furthermore, when viewed in a northwest-southeast orientation, the hypocenters cluster that defines the detachment appears to mimic the rugose extensional fault architecture imaged in the off shore to the west of Taiwan. This suggests that pre-existing faults on the margin, although oriented at a high angle to the convergence direction, are playing an active role in the development of thrust belt while still not being completely inverted. Eastward, the detachment at the basement-cover interface joins with an east-dipping hypocenter cluster that is interpreted to form a ramp that extends to greater than 20 km depth, into the middle crust. Above this ramp, basement rocks (P-wave > 5.2 km/s) are uplifted to

  4. Challenges Facing Managers in Managing Conflict in Schools in the South and South Central Regions of Botswana

    ERIC Educational Resources Information Center

    Morake, Nnior Machomi; Monobe, Ratau John; Dingwe, Stephonia

    2011-01-01

    The purpose of this study was to examine the challenges facing managers in managing conflict in schools of South and South Central Regions of Botswana. In this study, the schedule of interview was used to collect empirical data. A random sample of 50 school managers and deputy school managers was selected for interviews. Major findings of the…

  5. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    NASA Astrophysics Data System (ADS)

    Ager, Thomas A.

    2003-07-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ≥30,000 14C yr B.P. During the late middle Wisconsin interstadial (≥30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows ( Salix) and minor dwarf birch ( Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ≥30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca.11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs ( Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce ( Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island.

  6. Cultural remains in local and regional context on the central Alaska Peninsula: housepits, language, and cultural affinities at Marraatuq after 1000 B.P.

    PubMed

    McClenahan, Patricia L

    2010-01-01

    Professor Dumond's research on the Alaska Peninsula provided information that prior to 1,000 years ago people of both sides of the Alaska Peninsula shared material culture and exhibited subsistence interests that persisted into historic times, During the Late Precontact Era (ca. 1100 A.D. to mid-1700s) these Alutiiq societies shared cultural traits including language, house styles, and material culture with their relatives and neighbors on Kodiak Island. Until recently, few data were available regarding potential variability in house construction techniques, or styles and functions of Alutiiq semi-subterranean houses of this era found on the Alaska Peninsula, This paper provides examples of a few known prehistoric and historic Alaska Peninsula and Kodiak Alutiiq houses and presents previously unreported data from archaeological tests at Marraatuq on the Central Alaska Peninsula, Taken together with Dumond's 1998-1999 field work at Leader Creek and archaeological research on Kodiak Island, the work provides further evidence that interregional interaction was strong during the Late Precontact Era. However, large population centers and ranked political hierarchies probably were not hallmarks of central Alaska Peninsula communities during the Late Precontact Era and historic times as they were on the Kodiak and Aleutian islands. PMID:21495284

  7. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  8. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  9. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  10. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  11. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  12. Late Mesozoic and Cenozoic Tectonic History of South Central California

    NASA Astrophysics Data System (ADS)

    Engel, A. E. J.; Schultejann, P. A.

    1984-11-01

    The late Mesozoic-Cenozoic history of south central California is punctuated by at least five major tectonic events. The oldest of these involves Late Cretaceous drag folding and thrusting of epizonal shelf sediments westward over and to the north along the rising eastern margin of the Peninsular Ranges Batholith. These overthrusts, with associated drag folds and nappes, form imbricate stacks of metasediments, slices of plutons, and mylonites which overlie a regional core of Cretaceous granitic plutons of the Peninsular Ranges Batholith. A second, distinct kind of epizonal, low-temperature crustal displacement includes an episode of mid-Tertiary detachment faulting and folding. This represents the westerly extension of the detachment terrane of eastern California and western Arizona and Utah, superimposed upon the Cretaceous structural features, The mid-Tertiary motions involve major E-W extension and N-S compressive strain, with formation of east-trending antiformal "core complexes," remarkably parallel to a pervasive set of fold axes and B-lineations formed in the Cretaceous thrusting and folding. All of these features are repeatedly segmented and displaced by step-faulting as sial in the Salton Trough is fragmented and depressed 5 to 10 km below sea level at intervals throughout the Cenozoic. The irregular step-faulted interface of the Peninsular Ranges Batholith and Salton Trough is accentuated by a series of NE to SE striking left-lateral and dipslip faults with displacements of several to 10 kilometers. These appear to both predate and occur during movements along the San Andreas system. Pliocene-Pleistocene right-lateral faulting, a younger extension of the San Andreas displacements north of the Transverse Ranges, has broken and displaced all older structural features, with total net slip in south central California of perhaps 300 km. Total right-lateral slip along the several strands of the San Andreas system are measurable via reconstruction of the mosaic

  13. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.; Girina, Olga A.; Chibisova, Marina; Rybin, Alexander

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, and reports of unusual activity at or near eight separate volcanic centers in Alaska during 2009. The year was highlighted by the eruption of Redoubt Volcano, one of three active volcanoes on the western side of Cook Inlet and near south-central Alaska's population and commerce centers, which comprise about 62 percent of the State's population of 710,213 (2010 census). AVO staff also participated in hazard communication and monitoring of multiple eruptions at ten volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  14. Late Holocene megathrust earthquakes in south central Chile

    NASA Astrophysics Data System (ADS)

    Garrett, Ed; Shennan, Ian; Gulliver, Pauline; Woodroffe, Sarah

    2013-04-01

    A lack of comprehensive understanding of the seismic hazards associated with a subduction zone can lead to inadequate anticipation of earthquake and tsunami magnitudes. Four hundred and fifty years of Chilean historical documents record the effects of numerous great earthquakes; however, with recurrence intervals between the largest megathrust earthquakes approaching 300 years, seismic hazard assessment requires longer chronologies. This research seeks to verify and extend historical records in south central Chile using a relative-sea level approach to palaeoseismology. Our quantitative, diatom-based approaches to relative sea-level reconstruction are successful in reconstructing the magnitude of coseismic deformation during recent, well documented Chilean earthquakes. The few disparities between my estimates and independent data highlight the possibility of shaking-induced sediment consolidation in tidal marshes. Following this encouraging confirmation of the approach, we quantify land-level changes in longer sedimentary records from the centre of the rupture zone of the 1960 Valdivia earthquake. Here, laterally extensive marsh soils abruptly overlain by low intertidal sediments attest to the occurrence of four megathrust earthquakes. Sites preserve evidence of the 1960 and 1575 earthquakes and we constrain the timing of two predecessors to 1270 to 1410 and 1050 to 1200. The sediments and biostratigraphy lack evidence for the historically documented 1737 and 1837 earthquakes.

  15. Water movement in till of east-central South Dakota

    SciTech Connect

    Craven, S.J.; Ruedisili, L.C.; Barari, A.

    1985-01-01

    Factors that control the flow of water through till are poorly understood. Hydrographic analyses, field hydraulic conductivity measurements, and major-ion sampling were conducted on weathered and unweathered tills at 22 sites in east-central South Dakota. Water from a buried outwash aquifer was also chemically analyzed and carbon age dated. The upper part of most till has been weathered and exhibits extensive secondary permeability. Hydraulic conductivity values range from 10/sup -7/ to 10/sup -4/ cm/sec; typically 10 to 200 times higher than the hydraulic conductivity of unweathered till. Hydraulic gradients within weathered tills average seven times lower than within unweathered till. Water infiltrating below plant roots is believed to principally recharge and discharge the weathered till. Total dissolved solids were significantly higher in the weathered till than in the unweathered till. Water extracted from unweathered till is, in turn, up to three time higher in major-ion concentrations than water from the underlying outwash aquifer. Carbon-14 age dates from outwash aquifer water exceed 9000 years before present. Results indicate that Tittle to no water passes from the weathered till through the unweathered till into the buried outwash aquifer. Discharge from the weathered till is hypothesized to be primarily local lateral flow to sloughs, streams and ponds, combined with evapotranspiration losses during periods of high water table.

  16. Sonar Seafloor Exploration within the Central South Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Stubbs, C. C.; Sautter, L. R.; Harris, S. M.

    2006-12-01

    As part of the College of Charleston's Transect Program, research cruises conducted aboard the RV Savannah of the Skidaway Institution of Oceanography and the NOAA Ship Nancy Foster have explored and sampled several localities within the central portion of the South Atlantic Bight, the continental shelf region between Florida and Cape Hatteras, NC. Klein sidescan and Kongsberg multibeam sonar arrays collected seafloor images and bathymetric data that were processed by CofC undergraduate geology researchers using Caris HIPS/SIPS software. Several of the data sets have been ground-truthed using sediment grabs, footage from ROV cameras and SCUBA videography. Two of the prominent seafloor features discovered are (1) an outcropping hard-ground shelf-edge structure approximately 650 by 150 m, with 10 m relief. It is oriented parallel to shore in water depths of 60 m. Possible geological and biological influences on the structure's origin and morphology are being explored; and (2) a meandering river channel located on the mid-shelf, where water depth is approximately 22 m. Rock and sediment samples as well as video documentation of this feature reveal a channel with 1.5 m of relief, cut into the hard-ground, and includes coarse sands and abundant river pebbles. Additional shelf hard-ground features will be presented.

  17. Metamorphosed melange in the central Piedmont of South Carolina

    SciTech Connect

    Mittwede, S.K.; Maybin, A.H. III )

    1989-09-01

    The Enoree melange is exposed in the central Piedmont of South Carolina near the boundary between the Piedmont and Carolina terranes. The melange is composed of ultramafic and mafic blocks in a highly deformed matrix of biotite-feldspar-quartz gneiss which has a composition consistent with a felsic-to-intermediate volcanic precursor. The mafic and ultramafic blocks are separated chemically and petrographically into four compositional groups: metagabbro-clinopyroxenite, websterite, orthopyroxenite, and metasomatized (steatitized) orthopyroxenite. Based on their chemistry and mineralogy, the blocks are clearly exotic relative to their metavolcaniclastic( ) matrix and likely originated as parts of a plutonic suite from the basal or forward part of the Carolina arc terrane. If the Piedmont terrane-Carolina terrane boundary is a continent-arc suture, then the Enoree melange probably formed in the accretionary prism at this convergent margin. The matrix gneisses are interpreted as reworked volcanic debris shed by the Carolina arc terrane edifice and accumulated as graywacke in the accretionary deposits. West-vergent structures in the matrix suggest that the melange was emplaced to its present tectonostratigraphic position either during docking of the Carolina terrane or during widespread Alleghenian thrusting.

  18. Bimodal Recurrence Pattern of Tsunami in South Central Chile

    NASA Astrophysics Data System (ADS)

    Kempf, P.; Moernaut, J.; Van Daele, M. E.; Vandoorne, W.; Messens, F.; Vandenberghe, D.; Pino, M.; Urrutia, R.; De Batist, M. A. O.

    2015-12-01

    Establishing the recurrence time of large-scale tsunami is one of the main objectives of paleotsunami research, as it is fundamental for any tsunami risk assessment. Typically, the result is given in form of the mean recurrence time and a standard deviation as a range of uncertainty, assuming a normally distributed recurrence. We present a 5.5 ka long coastal lake paleotsunami record from south central Chile, which contains 17 tsunami deposits, 9 of which were previously unknown. Our record matches all 3 of the historically known tsunami, as well as all of the 5 known paleotsunami in the region without over- or underrepresentation. We used Bayesian age-depth modelling to calculate an age-depth model and extracted recurrence intervals for 16 recurrence intervals. Our findings confirm the previously published mean tsunami recurrence time on the Valdivia seismic segment of ~300 years. However, our analyses show a strongly bimodal recurrence pattern with one mode at ~115 years and the other mode at ~490 years. The least likely recurrence time between the modes is at ~300 years and coincides with the mean recurrence time. The reasons for the bimodal distribution remain speculative. They can be attributed to either spatial variability, e.g. incomplete segment rupture, splay fault rupture, up- or down-dip rupture, or to temporal variability, e.g. megathrust earthquake clustering, earthquake supercycles. Our findings highlight the importance of recognising the variability in tsunami recurrence patterns before using mean recurrence time for tsunami risk assessment.

  19. Water quality of Somerville Lake, south-central Texas

    USGS Publications Warehouse

    McPherson, Emma; Mendieta, H.B.

    1983-01-01

    Lake Somerville in south-central Texas has excellent water for municipal, industrial, and agricultural use. The total dissolved solids of the water averaged 220 milligrams per liter during a study from 1975-80. This shallow lake has a mean depth of 14 feet. The average annual inflow and discharge is greater than the volume of the lake. These two factors, along with wind action and the cooling of surface water during both summer and winter keep the lake well mixed and aerated. Even in summer the dissolved oxygen concentrations at the bottom of the lake usually were in excess of 50 percent of saturation. Dissolved iron concentrations are less than 50 micrograms per liter and dissolved manganese concentrations are under 40 micrograms per liter. These small concentrations are largely attributable to year-round oxygenated water. Homogeneous or near homogeneous concentrations of total phosphorus and inorganic nitrogen can occur at any time of the year throughout the lake. Dissolved chloride concentrations averaged 43 milligrams per liter and dissolved sulfate concentrations averaged 63 milligrams per liter. The total hardness of the water averaged about 110 milligrams per liter, placing it in the moderately hard classfication. (USGS)

  20. South Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP)

    SciTech Connect

    Dabberdt, W.F.; Viezee, W.

    1987-09-01

    The SCCCAMP field measurement program, conducted 3 September to 7 October 1985, is the most comprehensive mesoscale photochemical study of its type ever undertaken. The study area encompasses 2 x 10/sup 4/ km/sup 2/ of coastal and interior south-central California including the Santa Barbara Channel. A review of earlier experimental and analytical studies in the area is followed by the organizational framework and planning for this cooperative program. The experimental design and measurement systems are described. Existing ground-based meteorological and air pollution networks were supplemented by additional surface aerometric stations, dual Doppler radars, rawinsondes, and a network of Doppler acoustic profilers. Airborne measurement platforms included one dual-channel lidar, three aerometric sampling aircraft, /sup 3/ and a meteorological research aircraft. Gas tracer tests included 4-h releases of three perfluorocarbon gas tracers. Tracer measurements were made over two-day periods at 50 surface locations and aloft by aircraft with a near-realtime two-trap chromatographic system. Four multi-day intensive operational periods (IOP) are described, and illustrative results from one IOP are presented when extremely high ozone concentrations were observed at ground level (230 ppb) and aloft (290 ppb). The availability of the composite data base is indicated.

  1. South Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP).

    NASA Astrophysics Data System (ADS)

    Dabberdt, Waiter F.; Viezee, William

    1987-09-01

    The SCCCAMP field measurement program, conducted 3 September to 7 October 1985, is the most comprehensive mesoscale photochemical study of its type ever undertaken. The study area encompasses 2 × 104 km2 of coastal and interior south-central California including the Santa Barbara Channel. A review of earlier experimental and analytical studies in the area is followed by the organizational framework and planning for this cooperative program. The experimental design and measurement systems are described. Existing ground-based meteorological and air pollution networks were supplemented by additional surface aerometric stations, dual Doppler radars, rawinsondes, and a network of Doppler acoustic profilers. Airborne measurement platforms included one dual-channel lidar, three aerometric sampling aircraft, and a meteorological research aircraft. Gas tracer tests included 4-h releases of three perfluorocarbon gas tracers. Tracer measurements were made over two-day periods at 50 surface locations and aloft by aircraft with a near-realtime two-trap chromatographic system. Four multi-day intensive operational periods (IOP) are described, and illustrative results from one IOP are presented when extremely high ozone concentrations were observed at ground level (230 ppb) and aloft (290 ppb). The availability of the composite data base is indicated.

  2. Sparta sandstones: future exploration potential in south-central Louisiana

    SciTech Connect

    Lemoine, R.C.; Moslow, T.F.; Sassen, R.; Ferrell, R.E.

    1989-03-01

    The middle Eocene Sparta Formation is an important exploration objective within the prolific Eocene-Oligocene trend of south-central Louisiana. Cumulative production from 20 multiple-reservoir fields in the trend exceeds 269 million bbl of crude, 50 million bbl of condensate, and 1.5 billion ft/sup 3/ of gas. Additional reservoirs include the lower Eocene Wilcox, upper Eocene Cockfield, and Oligocene Frio Formations. This trend, coincident with the location of the Lower Cretaceous carbonate shelf edge, represents a series of unstable progradational clastic shelf margins. Principal structural traps are rollover anticlines, associated with down-to-the-basin growth faults, and salt domes. Recent Sparta production is associated with progradational barrier island complexes. Storm washover fan sandstones (22% porosity, 324 md permeability), tidal-inlet channel sandstones (20% porosity, 140 md permeability), and upper shoreface sandstones (19% porosity, 113 md permeability) represent the optimum-quality reservoir facies. Organic-rich basinal shales are source rocks for crude oil downdip from production where they are thermally mature. Lateral migration best explains emplacement of hydrocarbons in reservoirs.

  3. Quaternary tectonic setting of South-Central coastal California

    USGS Publications Warehouse

    Lettis, William R.; Hanson, Kathryn L.; Unruh, Jeffrey R.; McLaren, Marcia; Savage, William U.; Keller, Margaret A.

    2004-01-01

    Recent geodetic, geologic, and seismologic studies show that the south-central coast of California is a region of active Quaternary deformation. Northeast-directed crustal shortening is occurring in a triangular-shaped region between the Hosgri-San Simeon fault system on the west, the Southern Coast Ranges on the northeast, and the western Transverse Ranges on the south. We informally call this region the Los Osos domain. In this study, we conducted detailed geological, seismological, and geophysical investigations to characterize the nature and rates of deformation in the domain. Locations of active and potentially active faults and folds are compiled at a scale of 1:250,000 for the entire domain based primarily on onshore geologic data and offshore geophysical data. Crustal shortening in the domain is accommodated by a series of prominent northwest-trending reverse faults and localized folding. The reverse faults separate distinct structural blocks that have little or no internal deformation. Hangingwall blocks are being uplifted at rates of up to 0.2 mm/yr. Footwall blocks are either static or slowly subsiding at rates of 0.1 mm/yr or less, except for localized areas of concentrated subsidence directly adjacent to some faults. The cumulative rate of crustal shortening is about 1 to 2 mm/yr across the northern part of the domain based on observed geologic deformation. Cumulative shortening across the central and southern parts of the domain is poorly constrained by geologic data and may approach 2 to 3 mm/yr. Historical and instrumental seismicity generally are spatially associated with the uplifted blocks and bordering reverse faults to depths of about 10 km. Together with near-surface geological data and deeper crustal geophysical imaging that show high-angle faulting, the seismicity data indicate that the reverse faults probably extend to the base of the seismogenic crust. The base of the seismogenic crust may correspond with a mid-crustal detachment or

  4. Geochemistry of saline lakes of the northeastern Yukon Flats, east central Alaska

    NASA Astrophysics Data System (ADS)

    Hawkins, D. B.

    1985-01-01

    Above the Arctic Circle in the Yukon Flats of northeastern Alaska, shallow, brackish water ponds are rimmed with evaporite minerals such as trona (NaHCO3Na2CO3). These ponds form in an area of Alaska characterized by an extreme continental climate with about six inches of precipitation annually. Evaporite formation occurs because evaporation exceeds inflow. The hydrogeochemistry of the waters of the Yukon Flats was investigated to determine the origin of the ponds and evaporite minerals. Evaporation of the freshwater lakes will first precpitate calcite and ultimately form trona. The change in relative concentrations of Ca(+2), HCO3, and SO4 in going from river water to lake water is critical and indicates that sulfate reduction accompanied by bicarbonate formation is an essential process that produces an excess of HCO3 over CA(+2).

  5. Analysis of Regionally Detected Icequakes Using the STEEP Network, South-Central AK

    NASA Astrophysics Data System (ADS)

    O'Neel, S.; Leblanc, L.; Larsen, C.; Truffer, M.; Hansen, R.; Rupert, N.; Pavlis, G.; None, N.

    2007-12-01

    Glaciers produce seismic energy that is detectable from local to teleseismic distances. Glaciolgical processes including calving, surface crevassing, basal sliding and other, yet unresolved source processes are capable of producing recordable seismicity. Twenty-two broadband sensors deployed in south-central Alaska during the SainT Elias TEctonics and Erosion Project (STEEP) provide an excellent means to study glacier-generated seismicity at regional distances. These instruments surround over 7500 km2 of glacier area including the Bering Glacier, Bagley Icefield and the tidewater calving glaciers of Icy Bay (Yahtse, Guyot, Tyndal). Our analysis shows that icequakes nominally occur several times hourly, and can be separated from tectonic seismicity using their unique spectral characteristics and hypocenter locations. The events typically propagate over 50-75 km distances, but occasionally are recorded at stations over 150 km away from the energy source. Hypocenters for more than 1000 events were manually calculated through a 26-day interval during October 2006, and suggest that a majority of the icequakes are associated with calving at tidewater glaciers that terminate in Icy Bay. Events with similar time and frequency domain characteristics also occur at locations away from calving fronts, but less often, and their mechanical origin remains undetermined. Automated detections from a frequency domain event detector exhibit strong correlation with the handpicked time series, and extend our analysis to all available data collected during 2006. We present the time distribution of several categories of icequakes and compare these distributions to environmental variables such as precipitation, temperature and tides to explore potential forcing for observed variability in icequake occurrence.

  6. Distribution and characteristics of metamorphic belts in the south- eastern Alaska part of the North American Cordillera

    USGS Publications Warehouse

    Brew, D.A.; Himmelberg, G.R.; Loney, R.A.; Ford, A.B.

    1992-01-01

    The Cordilleran orogen in south-eastern Alaska includes 14 distinct metamorphic belts that make up three major metamorphic complexes, from east to west: the Coast plutonic-metamorphic complex; the Glacier Bay-Chichagof plutonic-metamorphic complex; and the Chugach plutonic-metamorphic complex. Each of these complexes is related to a major subduction event. The metamorphic history of the Coast complex is lengthy and is related to the Late Cretaceous collision of the Alexander and Wrangellia terranes and the Gravina overlap assemblage to the west against the Stikine terrane to the east. The metamorphic history of the Glacier Bay-Chichagof complex is relatively simple and is related to the roots of a Late Jurassic to late Early Cretaceous island arc. The metamorphic history of the Chugach is complicated and developed during and after the Late Cretaceous collision of the Chugach terrane with the Wrangellia and Alexander terranes. -from Authors

  7. Baseline channel morphology and bank erosion inventory of South Fork Campbell Creek at Campbell Tract, Anchorage, Alaska, 1999 and 2000

    USGS Publications Warehouse

    Curran, Janet H.

    2001-01-01

    South Fork Campbell Creek drains largely undeveloped land in Anchorage, Alaska, but supports heavy use near the Bureau of Land Management (BLM) Campbell Tract facility for recreation and environmental education. To help assess the impacts of human activities in the basin on biological communities, particularly aquatic and terrestrial biota, morphological changes to the channel bed and banks were monitored for 2 years. Erosion conditions and rates of change were measured and 11 transects were surveyed in three reaches of Campbell Creek near the BLM Campbell Creek Science Center in 1999. Repeat measurements at these 33 transects in 2000 documented noticeable differences between horizontal or vertical channel position at eight transects. Repeat measurements of 51 erosion pins at the survey transects provided details of bank erosion between the 2 years. Annual erosion rates at the erosion pins ranged from 0.81 foot per year of erosion to 0.16 foot per year of deposition.

  8. Ground-water investigation at the alluvial fan of the South Fork River, Anchorage, Alaska: results of test drilling, 1976

    USGS Publications Warehouse

    Dearborn, Larry L.

    1977-01-01

    In late 1976, at Anchorage, Alaska, a ground-water exploration well was drilled to a depth of 487 feet on the South Fork Eagle River fan near the confluence with the mainstream. The well penetrated four sand and gravel strata of low water-yielding capacity and extended 37 ft into metamorphic bedrock. Earth water-bearing stratum was pumped for several hours, and the best aquifer yield was found to be 1.7 gal/min/ft of drawdown. These test results support the conclusion, previously inferred from drilling data at a nearby test hole drilled in 1973, that there are no confined aquifers of large yield in the subsurface at this locality. (Woodard-USGS)

  9. Shallow-water habitat use by Bering Sea flatfishes along the central Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Hurst, Thomas P.

    2016-05-01

    Flatfishes support a number of important fisheries in Alaskan waters and represent major pathways of energy flow through the ecosystem. Despite their economic and ecological importance, little is known about the use of habitat by juvenile flatfishes in the eastern Bering Sea. This study describes the habitat characteristics of juvenile flatfishes in coastal waters along the Alaska Peninsula and within the Port Moller-Herendeen Bay system, the largest marine embayment in the southern Bering Sea. The two most abundant species, northern rock sole and yellowfin sole, differed slightly in habitat use with the latter occupying slightly muddier substrates. Both were more common along the open coastline than they were within the bay, whereas juvenile Alaska plaice were more abundant within the bay than along the coast and used shallow waters with muddy, high organic content sediments. Juvenile Pacific halibut showed the greatest shift in distribution between age classes: age-0 fish were found in deeper waters (~ 30 m) along the coast, whereas older juveniles were found in the warmer, shallow waters within the bay, possibly due to increased thermal opportunities for growth in this temperature-sensitive species. Three other species, starry flounder, flathead sole, and arrowtooth flounder, were also present, but at much lower densities. In addition, the habitat use patterns of spring-spawning flatfishes (northern rock sole, Pacific halibut, and Alaska plaice) in this region appear to be strongly influenced by oceanographic processes that influence delivery of larvae to coastal habitats. Overall, use of the coastal embayment habitats appears to be less important to juvenile flatfishes in the Bering Sea than in the Gulf of Alaska.

  10. Paleoclimatic significance of chemical weathering in loess-derived paleosols of subarctic central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Skipp, G.; Beann, J.; Budahn, J.; McGeehin, J.P.

    2008-01-01

    Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid-Wisconsin interstadiale. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most paleosols compared to parent loess, indicating depletion of plagioclase. In the clay fraction, smectite is present in Tanana and Yukon River source sediments, but is absent or poorly expressed in modern soils and paleosols, indicating depletion of this mineral also. Loss of both plagioclase and smectite is well expressed in soils and paleosols as lower SiO 2/TiO2. Carbonates are present in the river source sediments, but based on CaO/TiO2, they are depleted in soils and most paleosols (with one exception in the early-to-mid-Wisconsin period). Thus, most soil-forming intervals during past interglacial and interstadial periods in Alaska had climatic regimes that were at least as favorable to mineral weathering as today, and suggest boreal forest or acidic tundra vegetation. ?? 2008 Regents of the University of Colorado.

  11. Seasonal and Latitudinal Variations in Dissolved Methane from 42 Lakes along a North-South Transect in Alaska

    NASA Astrophysics Data System (ADS)

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K. C.; Anthony, P.; Thalasso, F.

    2013-12-01

    Armando Sepulveda-Jauregui,* Katey M. Walter Anthony,* Karla Martinez-Cruz,* ** Peter Anthony,* and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Northern lakes are important reservoirs and sources to the atmosphere of methane (CH4), a potent greenhouse gas. It is estimated that northern lakes (> 55 °N) contribute about 20% of the total global lake methane emissions, and that emissions from these lakes will increase with climate warming. Temperature rise enhances methane production directly by providing the kinetic energy to methanogenesis, and indirectly by supplying organic matter from thawing permafrost. Warmer lakes also store less methane since methane's solubility is inversely related to temperature. Alaskan lakes are located in three well-differentiated permafrost classes: yedoma permafrost with high labile carbon stocks, non-yedoma permafrost with lower carbon stocks, and areas without permafrost, also with generally lower carbon stocks. We sampled dissolved methane from 42 Alaskan lakes located in these permafrost cover classes along a north-south Alaska transect from Prudhoe Bay to the Kenai Peninsula during open-water conditions in summer 2011. We sampled 26 of these lakes in April, toward the end of the winter ice-covered period. Our results indicated that the largest dissolved methane concentrations occurred in interior Alaska thermokarst lakes formed in yedoma-type permafrost during winter and summer, with maximal concentrations of 17.19 and 12.76 mg L-1 respectively. In these lakes, emission of dissolved gases as diffusion during summer and storage release in spring were 18.4% and 17.4% of the annual emission budget, while ebullition (64.2 %) comprised the rest. Dissolved oxygen was inversely correlated with dissolved methane concentrations in both seasons; the

  12. Brookian sequence well log correlation sections and occurrence of gas hydrates, north-central North Slope, Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Collett, Timothy S.

    2013-01-01

    Gas hydrates are naturally occurring crystalline, ice-like substances that consist of natural gas molecules trapped in a solid-water lattice. Because of the compact nature of their structure, hydrates can effectively store large volumes of gas and, consequently, have been identified as a potential unconventional energy source. First recognized to exist geologically in the 1960s, significant accumulations of gas hydrate have been found throughout the world. Gas hydrate occurrence is limited to environments such as permafrost regions and subsea sediments because of the pressure and temperature conditions required for their formation and stability. Permafrost-associated gas hydrate accumulations have been discovered in many regions of the Arctic, including Russia, Canada, and the North Slope of Alaska. Gas hydrate research has a long history in northern Alaska. This research includes the drilling, coring, and well log evaluation of two gas hydrate stratigraphic test wells and two resource assessments of gas hydrates on the Alaska North Slope. Building upon these previous investigations, this report provides a summary of the pertinent well log, gas hydrate, and stratigraphic data for key wells related to gas hydrate occurrence in the north-central North Slope. The data are presented in nine well log correlation sections with 122 selected wells to provide a regional context for gas hydrate accumulations and the relation of the accumulations to key stratigraphic horizons and to the base of the ice-bearing permafrost. Also included is a well log database that lists the location, available well logs, depths, and other pertinent information for each of the wells on the correlation section.

  13. Mantle Xenoliths from Central and South Vietnam: Petrology and Geochemistry

    NASA Astrophysics Data System (ADS)

    Hauzenberger, Christoph; Konzett, Juergen; Nguyen, Hoang; Nguyen, Khoi

    2014-05-01

    Mantle xenoliths, spinel lherzolites and subordinate amounts of spinel harzburgites and pyroxenites, are commonly found in alkali basalts from south-central Vietnam. The basalts are part of widespread Neogene volcanism found in southern China and Indochina regions. Samples from different localities between the cities of Ban Me Thuot and Saigon were recovered. In addition one xenolith sample from an off-shore volcano SE of Ho Chi Minh City in the South China Sea was investigated. The mineral assemblage in most samples consists of the simple lherzolitic mineral assemblage Ol-Opx-Cpx-Sp. The Ol, Cpx and Opx crystals are equigranular while Sp occurs usually as smaller sized intersertal phase or as partly oriented inclusions in Cpx. Cpx II occurs in some samples as recrystallized "spongy rim" around Cpx I. Cpx I has a a very uniform composition between different samples with a typical XMg (=Mg/(Mg+Fe2+) of 0.92 to 0.98, a XNa (=Na/(Na+Ca) of 0.10 to 0.16, a Cr2O3 content of 0.6-0.9 wt. .% and Al2O3 values of c. 6 to 8 wt.%. Cpx II has a lower XNa and Al content as well as higher XMg and Cr content compared to Cpx I. Orthopyroxene typically has a XMg of c. 0.90 to 0.93. The XMg values for Ol differ slightly between different samples but are within 0.84 to 0.94. Spinel grains have a variable composition with XMg from 0.65 to 0.92 and XCr (Cr/Cr+Al+Fe3+) of 0.08 to 0.25. The use of the Cpx-Opx thermometer (BREY & KOEHLER, 1990) and the Al and Cr in Ol thermometer (DE HOOG et al., 2010) allowed to constrain the temperature with 800 to 1100 °C. Trace and rare earth element composition of Cpx was determined by LA-ICPMS. While most Cpx compositions are slightly depleted in LREE, typical for average depleted mantle compositions, some samples are strongly enriched in LREE indicating mantle metasomatic processes. The sample displaying the highest level of LREE enrichment in Cpx has the lowest calculated temperature (T = c. 800°C) and the highest Ni content in olivine (3000 ppm

  14. Stratigraphy and palaeoclimatic significance of Late Quaternary loess-palaeosol sequences of the Last Interglacial-Glacial cycle in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Bettis, E. Arthur, III; McGeehin, J.; Been, J.M.; Beget, J.E.; Pavich, M.J.; Stafford, Thomas W., Jr.; Stevens, D.A.S.P.

    2003-01-01

    Loess is one of the most widespread subaerial deposits in Alaska and adjacent Yukon Territory and may have a history that goes back 3 Ma. Based on mineralogy and major and trace element chemistry, central Alaskan loess has a composition that is distinctive from other loess bodies of the world, although it is quartz-dominated. Central Alaskan loess was probably derived from a variety of rock types, including granites, metabasalts and schists. Detailed stratigraphic data and pedologic criteria indicate that, contrary to early studies, many palaeosols are present in central Alaskan loess sections. The buried soils indicate that loess sedimentation was episodic, or at least rates of deposition decreased to the point where pedogenesis could keep ahead of aeolian input. As in China, loess deposition and pedogenesis are likely competing processes and neither stops completely during either phase of the loess/soil formation cycle. Loess deposition in central Alaska took place before, and probably during the last interglacial period, during stadials of the mid-Wisconsin period, during the last glacial period and during the Holocene. An unexpected result of our geochronological studies is that only moderate loess deposition took place during the last glacial period. Our studies lead us to conclude that vegetation plays a key role in loess accumulation in Alaska. Factors favouring loess production are enhanced during glacial periods but factors that favour loess accumulation are diminished during glacial periods. The most important of these is vegetation; boreal forest serves as an effective loess trap, but sparsely distributed herb tundra does not. Thus, thick accumulations of loess should not be expected where tundra vegetation was dominant and this is borne out by modern studies near the treeline in central Alaska. Much of the stratigraphic diversity of North American loess, including that found in the Central Lowlands, the Great Plains, and Alaska is explained by a new

  15. Characterization of the mississippian chat in South-central Kansas

    USGS Publications Warehouse

    Watney, W.L.; Guy, W.J.; Byrnes, A.P.

    2001-01-01

    To understand production from low resistivity-high porosity Mississippian chat reservoirs in south-central Kansas it is necessary to understand the nature of deposition and diagenesis, how tectonics is a factor, the lithofacies controls on petrophysical properties, and log response to these properties. The initial mudstones to sponge-spicule wacke-packstones were deposited in transgressive-regressive (T-R) cycles on a shelf to shelf margin setting, resulting in a series of shallowing-upward cycles. Sponge-spicule content appears to increase upward with increasing cycle thickness. After early silicification, inter- and post-Mississippian subaerial exposure resulted in further diagenesis, including sponge-spicule dissolution, vuggy porosity development in moldic-rich rocks, and autobrecciation. Meteoric water infiltration is limited in depth below the exposure surface and in distance downdip into unaltered, cherty Cowley Formation facies. Areas of thicker preserved chat and increased diagenesis can be correlated with structural lineaments and, in some areas, with recurrent basement block movement. Combination of folding or block fault movement prior to or during development of the basal Pennsylvanian unconformity, sponge-spicule concentration, and possibly thickness of overlying bioclastic wacke-grainstones resulted in variable reservoir properties and the creation of pods of production separated by nonproductive cherty dolomite mudstones. These events also resulted in alteration of the depositional cycles to produce a series of lithofacies that exhibit unique petrophysical properties. From bottom to top in a complete cycle seven lithofacies are present: (1) argillaceous dolomite mudstone, (2) argillaceous dolomite mudstone that has chert nodules, (3) clean dolomite mudstone that has nodular chert, (4) nodular to bedded chert, (5) autoclastic chert, (6) autoclastic chert that has clay infill, and (7) bioclastic wacke-grainstone. The uppermost cycle was terminated by

  16. Snowflake Size Distribution Measurements in South Central Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Tokay, A.; Bringi, V. N.; Huang, G.; Schoenhuber, M.; Bashor, P. G.; Hudak, D.; Jackson, G. S.; Petersen, W. A.

    2007-05-01

    In support of NASA's Global Precipitation Measurement (GPM) mission ground validation program, NASA's two laser optical disdrometers (Parsivel) and Colodaro State University (CSU) two-dimensional video disdrometer (2dvd) were deployed to a well-equipped precipitation observation site in South Central Ontario, Canada. The instruments were collocated and have been operating since late November 2006. So far, there has been numerous lake effect and synoptic winter storms over the site. In one event, parsivel disdrometers recorded 50 cm of snowfall. In addition, there have been at least 10 storms where the snow accumulation exceeded 4 cm. The leading objective of this study was to compare the parsivel and 2dvd size and fall velocity measurements for selected cases and relate the findings to the physical processes within and below the cloud. Unlike 2dvd, parsivel measures the maximum dimension of the snowflake in a single plane, while the fall velocity is calculated from the duration of the flake within the laser beam. The 2dvd samples the same flake in two planes from which fall velocity is obtained. The 2dvd also measures the maximum width and height in both planes. At the time of this abstract, two parsivels and 2dvd were operated nearly continuously for almost three months and preliminary data analysis is encouraging. The field site, which is known as Centre for Atmospheric Research Experiments (CARE), is an atmospheric research facility operated by the Air Quality Research Branch of the Meteorological Service of Canada and is located 80 km north of Toronto, Ontario, Canada in a rural agricultural and forested region. During the past three winters, a field campaign was conduced in support of Canadian CloudSat/CALIPSO validation project (c3vp). However, 2006-07 winter was the first since the satellites were in orbit. The coordinated efforts of aircraft missions over the CARE facility during the Intensive Operation Periods will enhance our understanding of cold cloud

  17. Hydrology of the Oakley Fan Area, south-central Idaho

    USGS Publications Warehouse

    Young, H.W.; Newton, G.D.

    1989-01-01

    The Oakley Fan area is a broad, crescent-shaped lowland along the southern margin of the Snake River Plain in south-central Idaho. Intensive groundwater development for irrigation has resulted in rapid water-level declines and, as a consequence, designation by the State of four Critical Groundwater Areas. Principal aquifers are in limestone, rhyolite, basalt, and alluvium. Annual water-level declines range from 3 ft to about 5 ft. Recharge to the groundwater system is from infiltration of surface water used for irrigation, precipitation on the surrounding mountains, infiltration of localized runoff, and upward movement of thermal water. Groundwater pumpage during the period 1979-84 averaged 173,000 acre-ft/yr. Surface and groundwater is predominantly a calcium bicarbonate type with variable concentrations of dissolved solids. Comparisons of silica and chloride concentrations and isotopic composition of groundwater were useful in determining areal extent of aquifers and movement of groundwater. A three-dimensional mathematical model of the Oakley Fan area was developed. The aquifer system was simulated in three phases: (1) Average 1979-84 hydrologic conditions, (2) 1910 hydrologic conditions, and (3) 1910-84 hydrologic conditions. Model simulation indicated that, for the period 1945-79, subsurface outflow declined from 327,000 acre-ft/yr to 215,000 acre-ft/yr. Simulated groundwater pumpage during the period 1945-79 was 3,000,000 acre-ft; simulated change in storage was 250,000 acre-ft. Simulations with the model approximate natural conditions and probably can be used to evaluate future changes in the hydrologic system.

  18. Diabetes in South and Central America: an update.

    PubMed

    Aschner, Pablo; Aguilar-Salinas, Carlos; Aguirre, Loreto; Franco, Laercio; Gagliardino, Juan Jose; de Lapertosa, Sylvia Gorban; Seclen, Segundo; Vinocour, Mary

    2014-02-01

    The estimated population of the South and Central America (SACA) Region is 467.6 million and 64% is in the age range of 20-79 years but the population pyramid and age distribution are changing. The average prevalence of diabetes in the Region is 8.0% and is expected to reach 9.8% by the year 2035. Prevalence is much lower in rural settings than in urban and the differences attributed to lifestyle changes may be a target for intervention. The indigenous population is a particularly vulnerable group needing special attention. On average, 24% of the adult cases with diabetes are undiagnosed but in some countries this is still as high as 50%. Health expenditure due to diabetes in the Region is around 9% of the global total. Inadequate glycemic control, defined as HbA1c >7%, is a strong predictor of chronic complications which increase resource use in the Region and less than half of the patients enrolled in diabetes care programmes are at target. Fifty percent or more of the adult population is overweight/obese and around one third of the adult population has metabolic syndrome using regional cutoffs for waist circumference. The number of people with IGT is almost equal to those with diabetes presenting an additional challenge for prevention. Children with type 1 diabetes represent only 0.2% of the total population with diabetes but the incidence may be increasing. In many places they have limited access to insulin, and even when available, it is not used appropriately. The available epidemiological data provide the background to act in developing national diabetes programmes which integrate diabetes care with cardiovascular prevention and promote diabetes prevention as well. PMID:24439209

  19. Enhanced recharge and karst, Edwards aquifer, south central Texas

    SciTech Connect

    Hammond, W.W. Jr. . Center for Water Research)

    1993-02-01

    Enhanced recharge is a water management strategy which can add significant quantities of ground water to the available water resources of the San Antonio region by utilizing the immense storage capacity of the unconfined zone of the Edwards aquifer. The Edwards aquifer presently is the sole source of water for a population of over 1,200,000, meeting public supply, industrial, and irrigation demands over a wide area of south central Texas. Valdina Farms Sinkhole is located adjacent to Seco Creek in Medina County and is in the recharge zone of the aquifer. Initial studies indicated that the sinkholes was capable of taking flood flows from Seco Creek and functioning as a recharge structure. Stream channels in the cavern system associated with Valdina Farms Sinkhole were incised into cave deposits and flood debris was present in the caverns at some distance from the sinkhole. Chemical analyses of samples of water from the cave and from nearby wells showed nitrate concentrations that decreased with distance from the cavern. Gradient of the potentiometric surface in the vicinity of the cave was very low, indicating high values of hydraulic conductivity for the aquifer. Based on evidence from these field studies a dam was constructed in 1982 on Seco Creek and a flood diversion channel was excavated to the sinkhole. Reservoir capacity is 2 acre-feet and design recharge rate is 3.8-6.7 m[sup 3]/sec. Annual recharge at the sinkhole has varied from 0 during periods of low runoff to 12,915 acre-feet.

  20. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, B.W.; Abbott, M.B.; Finney, B.P.; Kutchko, Barbara

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r2 = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varve-temperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation.

  1. High-pressure amphibolite facies dynamic metamorphism and the Mesozoic tectonic evolution of an ancient continental margin, east- central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Hansen, V.L.; Scala, J.A.

    1995-01-01

    Ductilely deformed amphibolite facies tectonites comprise two adjacent terranes in east-central Alaska: the northern, structurally higher Taylor Mountain terrane and the southern, structurally lower Lake George subterrane of the Yukon-Tanana terrane. The pressure, temperature, kinematic and age data are interpreted to indicate that the metamorphism of the Taylor Mountain terrane and Lake George subterrane took place during different phases of a latest Palaeozoic through early Mesozoic shortening episode resulting from closure of an ocean basin now represented by klippen of the Seventymile-Slide Mountain terrane. High- to intermediate-pressure metamorphism of the Taylor Mountain terrane took place within a SW-dipping (present-day coordinates) subduction system. High- to intermediate-pressure metamorphism of the Lake George subterrane and the structural contact zone occurred during NW-directed overthrusting of the Taylor Mountain, Seventymile-Slide Mountain and Nisutlin terranes, and imbrication of the continental margin in Jurassic time. -from Authors

  2. Coordination and establishment of centralized facilities and services of the University of Alaska ERTS survey of the Alaskan environment

    NASA Technical Reports Server (NTRS)

    Belon, A. E. (Principal Investigator); Miller, J. M.

    1973-01-01

    The author has identified the following significant results. The objective of this project is to provide a focus for the entire University of Alaska ERTS-1 effort (12 projects covering 10 disciplines and involving 8 research institutes and science departments). Activities have been concentrated on the implementation of the project's three primary functions: (1) coordination and management of the U of A ERTS-1 program, including management of the flow of data and data products; (2) acquisition, installation, test, operation, and maintanence of centralized facilities for processing ERTS-1, aircraft, and ground truth data; and (3) development of photographic and digital techniques for processing and interpreting ERTS-1 and aircraft data. With minor exceptions these three functions are now well-established and working smoothly.

  3. A geochemical sampling technique for use in areas of active alpine glaciation: an application from the central Alaska Range

    USGS Publications Warehouse

    Stephens, G.C.; Evenson, E.B.; Detra, D.E.

    1990-01-01

    In mountainous regions containing extensive glacier systems there is a lack of suitable material for conventional geochemical sampling. As a result, in most geochemical sampling programs a few stream-sediment samples collected at, or near, the terminus of valley glaciers are used to evaluate the mineral potential of the glaciated area. We have developed and tested a technique which utilizes the medial moraines of valley glaciers for systematic geochemical exploration of the glacial catchment area. Moraine sampling provides geochemical information that is site-specific in that geochemical anomalies can be traced directly up-ice to bedrock sources. Traverses were made across the Trident and Susitna glaciers in the central Alaska Range where fine-grained (clay to sand size) samples were collected from each medial moraine. These samples were prepared and chemically analyzed to determine the concentration of specific elements. Fifty pebbles were collected at each moraine for archival purposes and for subsequent lithologic identification. Additionally, fifty cobbles and fifty boulders were examined and described at each sample site to determine the nature and abundance of lithologies present in the catchment area, the extent and nature of visible mineralization, the presence and intensity of hydrothermal alteration and the existence of veins, dikes and other minor structural features. Results from the central Alaska Range have delineated four distinct multi-element anomalies which are a response to potential mineralization up-ice from the medial moraine traverse. By integrating the lithologic, mineralogical and geochemical data the probable geological setting of the geochemical anomalies is determined. ?? 1990.

  4. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Afghanistan 225.7704 Acquisitions of products and services from South Caucasus/Central...

  5. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Afghanistan 225.7704 Acquisitions of products and services from South Caucasus/Central...

  6. Particulate Matter Concentration Levels in South Central Richmond, California (Invited)

    NASA Astrophysics Data System (ADS)

    Bonner, B.; Byias, C.; Cuff, K. E.; Diaz, J.; Love, K.; Marks-Block, T.; McLane, F.; Mollique, Z.; Montes, E.; Ross, R.; Washington, B.

    2009-12-01

    South Central Richmond, California is the home of one of the nation’s most innovative green workforce training centers, Richmond BUILD - Green Jobs Training facility. A near constant stream of young people engaged in training activities, instructors, invited guests, and journalists of various ages can be seen moving in and out of the facility nearly every day of the week throughout a given year. Additionally, the comings and goings of young children and adults associated with a mid-sized elementary school just north of the facility contributes to the general area’s substantial human traffic. Unfortunately, however, a major highway, Interstate 580, a major thoroughfare, 23rd Street and a railway line operated by Burlington Northern Santa Fe, Union Pacific, and the Richmond Pacific Railroad frame the triangular area within which these two sites are situated. In addition, a major petrochemical complex and several shipping facilities are located less than three kilometers away north and west of this area. As part of a general assessment of air quality in this heavily human traveled area, we conducted a study of particulate matter (PM) concentrations over a five-month period beginning in August of 2009. Measurements were made at a variety of locations, and results were used to map the spatial distribution of PM of various sizes. Regions of high concentration levels were identified, and these particular areas then were monitored over time. Preliminary results of our study indicate that regions with high concentrations are consistent across the range of particle sizes measured, which suggests a common source for PM found in the study area. As these regions are located close to a major thoroughfare and railway line, we believe that diesel-burning vehicles are major contributors to the PM levels found in the study area. Time series results suggest a fairly strong correlation between higher than average PM concentrations and abnormally high wind gusts. On days when wind

  7. 78 FR 16028 - Waiver of Restriction on Assistance to the Central Government of South Sudan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Waiver of Restriction on Assistance to the Central Government of South Sudan Pursuant to Section 7031(b)(3... Section 7031(b)(1) of the Act with respect to South Sudan, and I hereby waive this restriction....

  8. Agrolandscape Research of Geosystems in the South of Central Siberia

    NASA Astrophysics Data System (ADS)

    Lysanova, G.; Soja, A. J.

    2012-12-01

    Minusinskaya basin, the area under research, is situated in the south of Central Siberia and is an agrarian region, which differs from another territories of Siberia. The territory provides for foodstuff not only its population but another regions as well. Nature-climate conditions favour the development of agriculture and cattle-breeding. Complex geographical study of rural lands, which is implemented by two approaches: a natural and industrial system block is necessary for rational use of agrolandscapes. Agrolandscapes are objects for rationalization of land management in agricultural regions. From our point of view application of a landscape map as a base for working out of agrolandscape map (Fig. 1a) and a map of agronatural potential of geosystems (Fig. 2), gives an opportunity to take stock of reserves of agricultural lands not only in quantitative but qualitative respects and also to determine the ways of optimal transformation of arable lands depending on nature conditions of regions and their development. Landscape maps that reflect differentiation of not only natural formations, changed by anthropogenious influence and also natural analogues, concern to a number of important tools of planning for optimal land use. The main principles of working out of typological landscape map of a medium scale aroused from targets and tasks of agrolandscape estimation of the territory [1]. The landscape map was worked out according to V.A. Nikolaev's methodology [2]: types of landscapes correlated with types of lands use, composition of cereals in rotation of crops, agro-techniques, crop capacity, climate indices, etc. Existing natural-agricultural systems are shown in the map. Their characteristics includes information about natural and agricultural blocks. Agronatural potential had been calculated by summarize estimations of its component parts. As a result of these calculations 30 arable agrolandscapes, marked out into the landscape map, were joined according to summ

  9. Variation in responses to spawning Pacific salmon among three south-eastern Alaska streams

    USGS Publications Warehouse

    Chaloner, D.T.; Lamberti, G.A.; Merritt, R.W.; Mitchell, N.L.; Ostrom, P.H.; Wipfli, M.S.

    2004-01-01

    1. Pacific salmon are thought to stimulate the productivity of the fresh waters in which they spawn by fertilising them with marine-derived nutrients (MDN). We compared the influence of salmon spawners on surface streamwater chemistry and benthic biota among three southeastern Alaska streams. Within each stream, reaches up- and downstream of barriers to salmon migration were sampled during or soon after spawners entered the streams. 2. Within streams, concentrations of dissolved ammonium and soluble reactive phosphorus (SRP), abundance of epilithon (chlorophyll a and ash-free dry mass) and biomass of chironomids were significantly higher in reaches with salmon spawners. In contrast, biomass of the mayflies Epeorus spp. and Rhithrogena spp. was significantly higher in reaches lacking spawners. 3. Among streams, significant differences were found in concentrations of dissolved ammonium, dissolved organic carbon, nitrate and SRP, abundance of epilithon, and the biomass of chironomids and Rhithrogena. These differences did not appear to reflect differences among streams in spawner density, nor the changes in water chemistry resulting from salmon spawners. 4. Our results suggest that the 'enrichment' effect of salmon spawners (e.g. increased streamwater nutrient concentrations) was balanced by other concurrent effects of spawners on streams (e.g. sediment disturbance). Furthermore, the collective effect of spawners on lotic ecosystems is likely to be constrained by conditions unique to individual streams, such as temperature, background water chemistry and light attenuation.

  10. Formation of lacustrine plains in west-central Alaska as a result of permafrost degradation and aggradation

    NASA Astrophysics Data System (ADS)

    Kanevskiy, M. Z.; Jorgenson, M. T.; Shur, Y.; O'Donnell, J.; Harden, J. W.; Fortier, D.

    2012-12-01

    Perennially frozen lacustrine sediments containing a large amount of ground ice comprise a significant part of the upper permafrost of the lowlands of west-central Alaska, including Koyukuk Flats and Innoko Flats. Study sites are located in the discontinuous permafrost zone, where permafrost was encountered mainly within uplifted peat plateaus. The upper part of studied sections is formed by frozen peat up to 3 m thick underlain by lacustrine silt, which is mostly ice-rich. Cryogenic structure of lacustrine sediments at different sites has common features: (1) prevalence of layered, braided, and reticulate cryostructures; (2) high variability in the ice content of sediments; (3) high density and low water content of soil aggregates separated by ice lenses. Volume of visible ice in silt reaches at places 40% and more. The thickness of ice lenses generally varies from 1 to 5 cm and occasionally reaches 10 cm. Remnants of peat plateaus are surrounded by unfrozen bogs and fens, formed as a result of thawing and settling of ice-rich lacustrine silt. Modern thermokarst scars initially form at places where ice-rich silt is not protected by a thick layer of organic material. Further development of thermokarst bogs includes lateral enlargement of thaw bulbs and collapsing of the margins of peat plateaus. Lacustrine silt within taliks is covered by woody peat accumulated under forests during the stage of permafrost plateau formation and then by aquatic sphagnum peat accumulated in taliks after collapse. We relate the formation of ice-rich lacustrine sediments to development of lake thermokarst, which affected ice-rich silty yedoma deposits during the transition from Pleistocene to Holocene. Terrain development in lacustrine lowlands of west-central Alaska includes five stages related to permafrost aggradation and degradation from the late Pleistocene to the present time: 1) formation of the ice-rich syngenetic permafrost (yedoma) during the late Pleistocene; 2) yedoma

  11. Glacimarine sedimentary processes, facies and morphology of the south-southeast Alaska shelf and fjords

    USGS Publications Warehouse

    Powell, R.D.; Molnia, B.F.

    1989-01-01

    High precipitation from Gulf of Alaska air masses can locally reach up to 800 cm a-1. This precipitation on tectonically active mountains creates cool-temperate glaciation with extremely active erosion and continuously renewed resources. High basal debris loads up to 1.5 m thick of pure debris and rapid glacial flow, which can be more than 3000 m a-1, combine to produce large volumes of siliciclastic glacimarine sediment at some of the highest sediment accumulation rates on record. At tidewater fronts of valley glaciers, sediment accumulation rates can be over 13 m a-1 and deltas commonly grow at about 106 m3 a-1. Major processes influencing glacimarine sedimentation are glacial transport and glacier-contact deposition, meltwater (subaerial and submarine) and runoff transport and deposition, iceberg rafting and gouging, sea-ice transport, wave action and storm reworking, tidal transport and deposition, alongshelf transport, sliding and slumping and gravity flows, eolian transport, and biogenic production and reworking. Processes are similar in both shelf and fjord settings; however, different intensities of some processes create different facies associations and geometries. The tectonoclimatic regime also controls morphology because bedrock structure is modified by glacial action. Major glacimarine depositional systems are all siliciclastic. They are subglacial, marginal-morainal bank and submarine outwash, and proglacial/paraglacial-fluvial/deltaic, beach, tidal flat/estuary, glacial fjord, marine outwash fjord and continental shelf. Future research should include study of long cores with extensive dating and more seismic surveys to evaluate areal and temporal extent of glacial facies and glaciation; time-series oceanographic data, sidescan sonar surveys and submersible dives to evaluate modern processes; biogenic diversity and production to evaluate paleoecological, paleobiogeographic and biofacies analysis; and detailed comparisons of exposed older rock of the

  12. Increased wetness confounds Landsat-derived NDVI trends in the central Alaska North Slope region, 1985–2011

    NASA Astrophysics Data System (ADS)

    Raynolds, Martha K.; Walker, Donald A.

    2016-08-01

    Satellite data from the circumpolar Arctic have shown increases in vegetation indices correlated to warming air temperatures (e.g. Bhatt et al 2013 Remote Sensing 5 4229–54). However, more information is needed at finer scales to relate the satellite trends to vegetation changes on the ground. We examined changes using Landsat TM and ETM+ data between 1985 and 2011 in the central Alaska North Slope region, where the vegetation and landscapes are relatively well-known and mapped. We calculated trends in the normalized difference vegetation index (NDVI) and tasseled-cap transformation indices, and related them to high-resolution aerial photographs, ground studies, and vegetation maps. Significant, mostly negative, changes in NDVI occurred in 7.3% of the area, with greater change in aquatic and barren types. Large reflectance changes due to erosion, deposition and lake drainage were evident. Oil industry-related changes such as construction of artificial islands, roads, and gravel pads were also easily identified. Regional trends showed decreases in NDVI for most vegetation types, but increases in tasseled-cap greenness (56% of study area, greatest for vegetation types with high shrub cover) and tasseled-cap wetness (11% of area), consistent with documented degradation of polygon ice wedges, indicating that increasing cover of water may be masking increases in vegetation when summarized using the water-sensitive NDVI.

  13. Geologic Model for Oil and Gas Assessment of the Kemik-Thomson Play, Central North Slope, Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Houseknecht, David W.

    2008-01-01

    A geologic model was developed to assess undiscovered oil and gas resources in the Kemik-Thomson Play of the Central North Slope, Alaska. In this model, regional erosion during the Early Cretaceous produced an incised valley system on the flanks and crest of the Mikkelsen High and formed the Lower Cretaceous unconformity. Locally derived, coarse-grained siliciclastic and carbonate detritus from eroded Franklinian-age basement rocks, Carboniferous Kekiktuk Conglomerate (of the Endicott Group), Lisburne Group, and Permian-Triassic Sadlerochit Group may have accumulated in the incised valleys during lowstand and transgression, forming potential reservoirs in the Lower Cretaceous Kemik Sandstone and Thomson sandstone (informal term). Continued transgression resulted in the deposition of the mudstones of the over-lying Cretaceous pebble shale unit and Hue Shale, which form top seals to the potential reservoirs. Petroleum from thermally mature facies of the Triassic Shublik Formation, Jurassic Kingak Shale, Hue Shale (and pebble shale unit), and the Cretaceous-Tertiary Canning Formation might have charged Thomson and Kemik sandstone reservoirs in this play during the Tertiary. The success of this play depends largely upon the presence of reservoir-quality units in the Kemik Sandstone and Thomson sandstone.

  14. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    NASA Technical Reports Server (NTRS)

    Beget, J. E.

    1993-01-01

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  15. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    NASA Astrophysics Data System (ADS)

    Beget, J. E.

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  16. Late summer heat-transfer regimes at adjacent permafrost and non-permafrost sites in central Alaska

    SciTech Connect

    Hinkel, K.M.; Nicholas, J. . Dept. of Geography); Outcalt, S.I. . Dept. of Geological Sciences)

    1992-01-01

    Hourly observations of soil temperature and a surrogate index of soil water ion concentration were collected during late summer from the upper 50 cm of soil at two adjacent sites in the discontinuous permafrost zone of central Alaska. One site is above permafrost while the other, 13 m away in an area of weak groundwater discharge, has no underlying permafrost. At the permafrost site, temperatures at the surface of the dry, porous organic mat experienced large diurnal variation but temperature amplitude was strongly attenuated with depth. Steep thermal gradients induce diffusion of water vapor from the base of the active layer toward the surface. Evaporative cooling thus inhibits heat penetration and maintains subfreezing temperatures at depth. However, infiltration of precipitation is an effective method of transporting sensible heat to the base of the active layer and extending seasonal thaw depth above permafrost. Conversely, at the groundwater seep site, saturation maintained by throughflow damps temperature variation with time and depth, and precipitation has little impact on the evolution of the thermal regime. Soil conditions and precipitation patterns strongly influence the nonconductive heat flux component and produce complex spatial and temporal thaw patterns.

  17. Microbial enzyme activities of peatland soils in south central Alaska lowlands

    EPA Science Inventory

    Microbial enzyme activities related to carbon and nutrient acquisition were measured on Alaskan peatland soils as indicators of nutrient limitation and biochemical sustainability. Peat decomposition is mediated by microorganisms and enzymes that in turn are limited by various ph...

  18. Regional vertical tectonic displacement of shorelines in south- central Alaska during and between great earthquakes

    USGS Publications Warehouse

    Plafker, G.

    1990-01-01

    Reviews the setting of the 1964 earthquake and the unprecedented tectonic deformation that accompanied it. Outlines research directed towards defining the deformation that occurs between great earthquakes (interseismic part of the seismic cycle) and the longterm history of deformation over repeated seismic cycles in the earthquake-affected region, emphasizing work in progress. An understanding of this record of deformation is basic for evaluating how frequently 1964-type events recur in this same region, for improved understanding for the earthquake cycle in great subduction-zone seismotectonic events, and for predicting future great earthquakes in this and tectonically similar regions elsewhere. -from Author

  19. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, BW; Abbott, MB; Finney, BP; Kutchko, B

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve-thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r (2) = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varvetemperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation. Varve-inferred summer temperatures and precipitation decreased after 730 AD, averaging 0.4A degrees C above the last millennial average (LMA = 4.2A degrees C) from 730 to 850 AD, and 0.1A degrees C above the LMA from 850 to 980 AD. Cooling culminated between 980 and 1030 AD with temperatures 0.7A degrees C below the LMA. Varve-inferred summer temperatures increased between 1030 and 1620 AD to the LMA, though the period between 1260 and 1350 AD was 0.2A degrees C below the LMA. Although there is no equivalent to the European Medieval Warm Period in the Blue Lake record, two warm intervals occurred from 1350 to 1450 AD and 1500 to 1620 AD (0.4 and 0.3A degrees C above the LMA, respectively). During the Little Ice Age (LIA; 1620 to 1880 AD), inferred summer temperature averaged 0.2A degrees C below the LMA. After 1880 AD, inferred summer temperature increased to 0.8A degrees C above the LMA, glaciers retreated, but aridity persisted based on a number of regional paleoclimate records. Despite warming and glacial retreat, varve thicknesses have not achieved pre-730 AD levels. This reflects limited sediment availability and transport due to a less extensive retreat compared to the first millennium, and continued relative aridity. Overall, the Blue Lake record is similar to varve records from the

  20. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Iraq or Afghanistan 225.7704 Acquisitions of products and services from South...

  1. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Iraq or Afghanistan 225.7704 Acquisitions of products and services from South...

  2. Physical characteristics of stream subbasins in the Blue Earth River Basin, south-central Minnesota and north-central Iowa

    USGS Publications Warehouse

    Lorenz, D.L.; Payne, G.A.

    1992-01-01

    This report presents data describing the physical characteristics of stream basins upstream from selected points on streams in the Blue Earth River basin, located in south-central Minnesota and north-central Iowa. The physical characteristics are the drainage area of the basin, the percentage area of the basin covered only by lakes, the percentage area of the basin covered by both lakes and wetlands, the main-channel length, and the mainchannel slope. The points on the stream include outlets of subbasins of at least five square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey gaging stations.

  3. Late Mesozoic and Cenozoic thermotectonic evolution of the central Brooks Range and adjacent North Slope foreland basin, Alaska: Including fission track results from the Trans-Alaska Crustal Transect (TACT)

    USGS Publications Warehouse

    O'Sullivan, P. B.; Murphy, J.M.; Blythe, A.E.

    1997-01-01

    Apatite fission track data are used to evaluate the thermal and tectonic history of the central Brooks Range and the North Slope foreland basin in northern Alaska along the northern leg of the Trans-Alaska Crustal Transect (TACT). Fission track analyses of the detrital apatite grains in most sedimentary units resolve the timing of structures and denudation within the Brooks Range, ranging in scale from the entire mountain range to relatively small-scale folds and faults. Interpretation of the results indicates that rocks exposed within the central Brooks Range cooled rapidly from paleotemperatures 110?? to 50??C during discrete episodes at ???100??5 Ma, ???60??4 Ma, and ???24??3 Ma, probably in response to kilometer-scale denudation. North of the mountain front, rocks in the southern half of the foreland basin were exposed to maximum paleotemperatures 110??C in the Late Cretaceous to early Paleocene as a result of burial by Upper Jurassic and Cretaceous sedimentary rocks. Rapid cooling from these elevated paleotemperatures also occurred due to distinct episodes of kilometer-scale denudation at ???60??4 Ma, 46??3 Ma, 35??2 Ma, and ???24??3 Ma. Combined, the apatite analyses indicate that rocks exposed along the TACT line through the central Brooks Range and foreland basin experienced episodic rapid cooling throughout the Late Cretaceous and Cenozoic in response to at least three distinct kilometer-scale denudation events. Future models explaining orogenic events in northern Alaska must consider these new constraints from fission track thermochronology. Copyright 1997 by the American Geophysical Union.

  4. Preliminary geology of eastern Umtanum Ridge, South-Central Washington

    SciTech Connect

    Goff, F.E.

    1981-01-01

    The basalt stratigraphy and geologic structures of eastern Umtanum Ridge have been mapped and studied in detail to help assess the feasibility of nuclear waste terminal storage on the Hanford Site in southeastern Washington State. Eastern Umtanum Ridge is an asymmetric east-west-trending anticline of Columbia River basalt that plunges 5 degrees eastward into the Pasco Basin. Geologic mapping and determination of natural remanent magnetic polarity and chemical composition reveal that flows of the Pomona and Umatilla Members (Saddle Mountains Basalt), Priest Rapids and Frenchman Springs Members (Wanapum Basalt), and Grande Ronde Basalt were erupted as fairly uniform sheets. The Wahluke and Huntzinger flows (Saddle Mountains Basalt) fill a paleovalley cut into Wanapum Basalt. No evidence was found to indicate Quaternary-age movement on any structures in the map area. The basalt strata on the south limb of the Umtanum anticline display relatively little tectonic deformation since Miocene-Pliocene time. Thus, the buried south flank of Umtanum Ridge may provide an excellent location for a nuclear waste repository beneath the Hanford Site.

  5. 1994 Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; Doukas, Michael P.; McGimsey, Robert G.

    1995-01-01

    During 1994, the Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, or false alarms at nine volcanic centers-- Mount Sanford, Iliamna, the Katmai group, Kupreanof, Mount Veniaminof, Shishaldin, Makushin, Mount Cleveland and Kanaga (table 1). Of these volcanoes, AVO has a real time, continuously recording seismic network only at Iliamna, which is located in the Cook Inlet area of south-central Alaska (fig. 1). AVO has dial-up access to seismic data from a 5-station network in the general region of the Katmai group of volcanoes. The remaining unmonitored volcanoes are located in sparsely populated areas of the Wrangell Mountains, the Alaska Peninsula, and the Aleutian Islands (fig. 1). For these volcanoes, the AVO monitoring program relies chiefly on receipt of pilot reports, observations of local residents and analysis of satellite imagery.

  6. Multistory duplexes with forward dipping roofs, north central Brooks Range, Alaska

    USGS Publications Warehouse

    Wallace, W.K.; Moore, T.E.; Plafker, G.

    1997-01-01

    The Endicott Mountains allochthon has been thrust far northward over the North Slope parautochthon in the northern Brooks Range. Progressively younger units are exposed northward within the allochthon. To the south, the incompetent Hunt Fork Shale has thickened internally by asymmetric folds and thrust faults. Northward, the competent Kanayut Conglomerate forms a duplex between a floor thrust in Hunt Fork and a roof thrust in the Kayak Shale. To the north, the competent Lisburne Group forms a duplex between a floor thrust in Kayak and a roof thrust in the Siksikpuk Formation. Both duplexes formed from north vergent detachment folds whose steep limbs were later truncated by south dipping thrust faults that only locally breach immediately overlying roof thrusts. Within the parautochthon, the Kayak, Lisburne, and Siksikpuk-equivalent Echooka Formation form a duplex identical to that in the allochthon. This duplex is succeeded abruptly northward by detachment folds in Lisburne. These folds are parasitic to an anticlinorium interpreted to reflect a fault-bend folded horse in North Slope "basement," with a roof thrust in Kayak and a floor thrust at depth. These structures constitute two northward tapered, internally deformed wedges that are juxtaposed at the base of the allochthon. Within each wedge, competent units have been shortened independently between detachments, located mainly in incompetent units. The basal detachment of each wedge cuts upsection forward (northward) to define a wedge geometry within which units dip regionally forward. These dips reflect forward decrease in internal structural thickening by forward vergent folds and hindward dipping thrust faults. Copyright 1997 by the American Geophysical Union.

  7. Bibliography for Hayes, Spurr, Crater Peak, Redoubt, Iliamna, Augustine, Douglas, and Aniakchak volcanoes, Alaska

    USGS Publications Warehouse

    Lemke, K.J.; May, B.A.; Vanderpool, A.M.

    1995-01-01

    Alaska has more than 40 active volcanoes, many of which are close to the major population centers of south-central Alaska. This bibliography was compiled to assist in the preparation of volcano hazard evaluations at Cook Inlet volcanoes. It lists articles, reports, and maps about the geology and hydrology of Hayes, Spurr, Redoubt, Iliamna, Augustine, and Douglas volcanoes in the Cook Inlet region as well as Aniakchak Volcano on the Alaska Peninsula. References on the biology and archaeology of areas surrounding each volcano also are included because they may provide useful background information.

  8. Late Cretaceous Middle Fork caldera and its resurgent granite porphyry intrusion, east-central Alaska

    NASA Astrophysics Data System (ADS)

    Bacon, C. R.; Dusel-Bacon, C.; Aleinikoff, J. N.; Slack, J. F.

    2012-12-01

    to have been exposed by erosion of thick intracaldera tuff from an asymmetric resurgent dome. The Middle Fork of the North Fork of the Fortymile River cuts an arcuate valley into and around the caldera on the west and north, and may have cut down from an original caldera moat. Proximal outflow tuff, and thus the 69 Ma land surface, remains at the west margin of the caldera structure. The Middle Fork caldera lies within a region of Paleozoic metamorphic rocks and Mesozoic plutons bounded by northeast-trending faults. To the northwest, Cretaceous plutonic rocks are widely exposed, indicating greater exhumation. The Middle Fork is a relatively well preserved caldera within a broad region of Alaska and adjacent Yukon that contains Late Cretaceous plutons and, in the less deeply exhumed blocks, silicic volcanic rocks.

  9. Use of Radarsat-2 Polarimetric SAR Images for Fuel Moisture Mapping in Alaska Boreal Forests and South Africa Savannahs

    NASA Astrophysics Data System (ADS)

    Leblon, B.; Bourgeau-Chavez, L. L.; Kong, M.; Buckley, J. R.; Mathieu, R. M.; Charbonneau, F.; Gross, C. P.; Naidoo, L.

    2014-12-01

    The study reported a comparison between two Radarsat-2 polarimetric SAR (polSAR) images from extreme dry versus wet conditions are compared in an effort to determine the value of using polarimetric SAR data for estimating fuel moisture over South Africa savannahs and Alaska boreal forests. The savannahs study area is located into the Kruger National Park area and has 36 sites of lowveld savannas from bare overgrazed sites to medium-dense savannahs. The boreal forest study area has a chronosequence of black spruce ecosystems (recent burns, shrub-dominated regenerating forests , open canopied forests, moderately dense forest cover). Both study areas have a fairly level topography suitable for radar studies. The polSAR images were acquired using the same beam mode (FQ5 (23-25° incidence angle over the boreal sites, FQ15 (34.47-36.05° incidence angle) over the savannahs sites). Over each study area, soil moisture and vegetation structural data were measured in situ concurrently to the acquisition of the SAR imagery. The polSAR images were filtered for speckle noise using a Lee sigma filter and several polarimetric products were computed, such as those directly derived from the images (single linear and polairzed backscatters, polarimetric discriminators) and from target decompositions (Freeman-Durden, new van Zyl, Cloude-Pottier). Because most of these variables have a different unit, a normalized difference (in %) for each variable was calculated using the median values of the dry and wet dates for easier comparison of variable changes between the dates. Over both study areas, the normalized difference between wet and dry conditions was lower when higher tree canopy occurs. Results show utility of C-HH and C-RR polarized backscatters. Several polarimetric discriminators (dmin, Pr max, Pr min, Smax, Smin) were also significantly affected by the soil wetness. The Freeman Durden and van Zyl decomposition parameters outperformed the Cloude-Pottier decomposition

  10. Late Cenozoic structure and stratigraphy of south-central Washington

    SciTech Connect

    Reidel, S.P. |; Campbell, N.P.; Fecht, K.R.; Lindsey, K.A.

    1993-09-01

    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs.

  11. Lisburne Group (Mississippian-Lower Permian) petrography, paragenesis, and hydrocarbon potential, central Brooks Range, Alaska

    SciTech Connect

    Krutak, P.R.

    1989-03-01

    Subsurface Lisburne Group (Wahoo) rocks at Prudhoe Bay-Kuparuk fields produce 2 million bbl of oil/day and contain 2-3 billion bbl of oil in place. Lisburne reservoirs are early diagenetic dolomites encased in thick platform carbonates. Petrographic and geochemical study of 264 samples from eight newly discovered surface Lisburne sections comprising 4568 ft of strata in the Central Brooks Range provide new data concerning paragenesis and hydrocarbon potential of Lisburne facies farther west. A generalized paragenetic sequence for Lisburne equivalents of this region is (1) initial carbonate skeletal growth (both aragonite and calcite) during the Carboniferous, (2) subsequent recrystallization and inversion of aragonite to calcite, the change to calcite proceeding throughout late Paleozoic and Permian-Triassic time, (3) dolomitization in the Middle and Late Carboniferous, (4) chertification and silicification, postdating slightly or overlapping dolomitization, (5) development of porosity (moldic, intracrystal, etc.) in the middle to late Mesozoic, (6) formation of fracture porosity concurrent with the Brooks Range orogeny during Middle Jurassic-Cretaceous time, (7) oil generation, migration, and emplacement in Late Cretaceous-Tertiary time. Lisburne dolomites from the Central Brooks Range bear heavy hydrocarbons. Rock-Eval pyrolysis indicates part of the section is in the oil window and near the peak wet-gas generation zone. Shale samples from this region display thermal alteration indices and vitrinite reflectance values near the oil floor and also indicate potential for sourcing dry gas. Conodont color alteration indices show part of the Lisburn could produce dry gas.

  12. Effects of drought in central and south Texas

    USGS Publications Warehouse

    Thomas, H.E.; Others

    1963-01-01

    The effects of drought upon ground-water storage and discharge, and upon streamflow, vary tremendously in the central third of Texas (the area from the Panhandle to the Gulf of Mexico). Extremes are represented by (a) the Llano Estacado, where the drought had negligible effect upon ground-water resources, which are being progressively depleted by pumping for irrigation; and (b) the Balcones fault-zone aquifer west of San Antonio, whose storage and natural discharge declined substantially during the drought, but increased even more rapidly during succeeding years of more abundant precipitation.

  13. The last termination in the central South Atlantic

    NASA Astrophysics Data System (ADS)

    Ljung, Karl; Holmgren, Sofia; Kylander, Malin; Sjolte, Jesper; Van der Putten, Nathalie; Kageyama, Masa; Porter, Charles T.; Björck, Svante

    2015-09-01

    Lake sediments and peat deposits from two basins on Nightingale Island (37°S), in the Tristan da Cunha archipelago, South Atlantic, have been analyzed. The studies were focused on the time period 16.2-10.0 cal ka BP, determined by 36 14C dates from the two sequences. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, C and N analyzes, stable isotopes (13C and 15N), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. In addition, climate model simulations were carried out. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. The climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich 1 event in the north and a southward displacement of the ITCZ. The development on the island after 16.2 cal ka BP is determined by the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). The period 16.2-14.75 cal ka BP was characterized by varying influence from SHW and with STF situated south of Tristan da Cunha, ending with a humidity peak and cooler conditions. The stable conditions 14.7-14.1 cal ka BP with cool and fairly arid conditions imply that STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The most unstable period, 14.1-12.7 cal ka BP, indicates incessant latitudinal shifts of the zonal circulation, perhaps related to climate variability in the Northern Hemisphere and bipolar seesaw mechanisms as the strength of the Atlantic Meridional Overturning Circulation (AMOC) varied. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming

  14. The Last Termination in the Central South Atlantic

    NASA Astrophysics Data System (ADS)

    Sjolte, J.; Ljung, K.; Holmgren, S.; Kylander, M. E.; Van der Putten, N.; Kageyama, M.; Porter, C. T., Jr.; Bjorck, S.

    2015-12-01

    We present results from analysis of lake sediments and peat deposits from two basins on Nightingale Island (37°S), in the Tristan da Cunha archipelago, South Atlantic. The studies were focused on the time period 16.2-10.0 cal ka BP. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, bulk C and N content, stable isotopes (13C and 15N), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. Climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich 1 event in the north and a southward displacement of the ITCZ. We interpret the results as being related to the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). During 16.2-14.75 cal ka BP the SHW and STF were situated south of Tristan da Cunha. The data indicates moderate variability ending with a humidity peak and cooler conditions. The conditions during 14.7-14.1 cal ka BP were more stable with cool and arid conditions implying that the STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The period 14.1-12.7 cal ka BP indicates incessant latitudinal shifts of the zonal circulation, perhaps related the bipolar seesaw mechanisms. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming seems to have occurred in the earliest part of the Holocene, but this period was also characterized by humidity shifts, possibly an effect of retraction and expansion phases of SHW during AMOC variations in the north.

  15. Three-dimensional model of an ultramafic feeder system to the Nikolai Greenstone mafic large igneous province, central Alaska Range

    USGS Publications Warehouse

    Glen, J.M.G.; Schmidt, J.M.; Connard, G.G.

    2011-01-01

    The Amphitheater Mountains and southern central Alaska Range expose a thick sequence of Triassic Nikolai basalts that is underlain by several mafic-ultramafic complexes, the largest and best exposed being the Fish Lake and Tangle (FL-T) mafic-ultramafic sills that flank the Amphitheater Mountains synform. Three-dimensional (3-D) modeling of gravity and magnetic data reveals details of the structure of the Amphitheater Mountains, such as the orientation and thickness of Nikolai basalts, and the geometry of the FL-T intrusions. The 3-D model (50 ?? 70 km) includes the full geographic extent of the FL-T complexes and consists of 11 layers. Layer surfaces and properties (density and magnetic susceptibility) were modified by forward and inverse methods to reduce differences between the observed and calculated gravity and magnetic grids. The model suggests that the outcropping FL-T sills are apparently connected and traceable at depth and reveals variations in thickness, shape, and orientation of the ultramafic bodies that may identify paths of magma flow. The model shows that a significant volume (2000 km3) of ultramafic material occurs in the subsurface, gradually thickening and plunging westward to depths exceeding 4 km. This deep ultramafic material is interpreted as the top of a keel or root system that supplied magma to the Nikolai lavas and controlled emplacement of related magmatic intrusions. The presence of this deep, keel-like structure, and asymmetry of the synform, supports a sag basin model for development of the Amphitheater Mountains structure and reveals that the feeders to the Nikolai are much more extensive than previously known. Copyright 2011 by the American Geophysical Union.

  16. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  17. Detrital zircon geochronology of the Adams Argillite and Nation River Formation, east-central Alaska, U.S.A

    USGS Publications Warehouse

    Gehrels, G.E.; Johnsson, M.J.; Howell, D.G.

    1999-01-01

    The Cambrian Adams Argillite and the Devonian Nation River Formation are two sandstone-bearing units within a remarkably complete Paleozoic stratigraphic section in east-central Alaska. These strata, now foreshortened and fault-bounded, were originally contiguous with miogeoclinal strata to the east that formed as a passive-margin sequence along the northwestern margin of the North American continent. Seventy-five detrital zircon grains from the Adams Argillite and the Nation River Formation were analyzed in an effort to provide constraints on the original sources of the grains, and to generate a detrital zircon reference for miogeoclinal strata in the northern Cordillera. Thirty-five single zircon grains from a quartzite in the Adams Argillite yield dominant age clusters of 1047-1094 (n = 6), 1801-1868 (n = 10), and 2564-2687 (n = 5) Ma. Forty zircons extracted from a sandstone in the Nation River Formation yield clusters primarily of 424-434 (n = 6), 1815-1838 (n = 6), 1874-1921 (n = 7), and 2653-2771 (n = 4) Ma. The Early Proterozoic and Archean grains in both units probably originated in basement rocks in a broad region of the Canadian Shield. In contrast, the original igneous sources for mid-Protcrozoic grains in the Adams Argillite and ??? 430 Ma grains in the Nation River Formation are more difficult to identify. Possible original sources for the mid-Proterozoic grains include: (1) the Grenville Province of eastern Laurentia, (2) the Pearya terrane along the Arctic margin, and (3) mid-Proterozoic igneous rocks that may have been widespread along or outboard of the Cordilleran margin. The ??? 430 Ma grains may have originated in: (1) arc-type sources along the Cordilleran margin, (2) the Caledonian orogen, or (3) a landmass, such as Pearya, Siberia, or crustal fragments now in northern Asia, that resided outboard of the Innuitian orogen during mid-Paleozoic time. Copyright ?? 1999, SEPM (Society for Sedimentary Geology).

  18. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false South Central Coast Intrastate Air Quality Control Region. 81.166 Section 81.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of Air Quality Control Regions § 81.166...

  19. Detection of east/central/south African genotype of chikungunya virus in Myanmar, 2010.

    PubMed

    Tun, Mya Myat Ngwe; Thant, Kyaw Zin; Inoue, Shingo; Nabeshima, Takeshi; Aoki, Kotaro; Kyaw, Aung Kyaw; Myint, Tin; Tar, Thi; Maung, Kay Thwe Thwe; Hayasaka, Daisuke; Morita, Kouichi

    2014-08-01

    In 2010, chikungunya virus of the East Central South African genotype was isolated from 4 children in Myanmyar who had dengue-like symptoms. Phylogenetic analysis of the E1 gene revealed that the isolates were closely related to isolates from China, Thailand, and Malaysia that harbor the A226V mutation in this gene. PMID:25062511

  20. Looking south through east portion of Centralized Work Equipment (C.W.E.) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking south through east portion of Centralized Work Equipment (C.W.E.) Storage Shed (Bldg. 126). Note overhead monorails for material-handling hoists. This shed stored track maintenance materials - Atchison, Topeka, Santa Fe Railroad, Albuquerque Shops, C.W.E. Storage Shed, 908 Second Street, Southwest, Albuquerque, Bernalillo County, NM

  1. Detection of East/Central/South African Genotype of Chikungunya Virus in Myanmar, 2010

    PubMed Central

    Tun, Mya Myat Ngwe; Thant, Kyaw Zin; Inoue, Shingo; Nabeshima, Takeshi; Aoki, Kotaro; Kyaw, Aung Kyaw; Myint, Tin; Tar, Thi; Maung, Kay Thwe Thwe; Hayasaka, Daisuke

    2014-01-01

    In 2010, chikungunya virus of the East Central South African genotype was isolated from 4 children in Myanmyar who had dengue-like symptoms. Phylogenetic analysis of the E1 gene revealed that the isolates were closely related to isolates from China, Thailand, and Malaysia that harbor the A226V mutation in this gene. PMID:25062511

  2. U.S. Blacks' Perceptions, Experiences, and Scholarship regarding Central and South America--1822 to 1959

    ERIC Educational Resources Information Center

    Fikes, Robert, Jr.

    2006-01-01

    Instances of U.S. Black Americans having direct contact with the inhabitants of Central and South America, whose majority populations are not Black, can be traced back to the early nineteenth century. Slaves and freemen were aware of the possibility of a better life in these regions and a few found their way there to experience trials,…

  3. 40 CFR 81.105 - South Central Pennsylvania Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES... Region. The South Central Pennsylvania Intrastate Air Quality Control Region consists of the territorial... territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C....

  4. Atrazine in Source Water Intended for Artificial Ground-Water Recharge, South-Central Kansas

    USGS Publications Warehouse

    Christensen, Victoria G.; Ziegler, Andrew C.

    1998-01-01

    Atrazine, an herbicide commonly applied to row crops, is of concern because of potential effects on water quality. This fact sheet describes atrazine in water from the Little Arkansas River in south-central Kansas. The river is being evaluated as a source of artificial recharge into the Equus Beds aquifer, which provides water for the city of Wichita.

  5. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false South Central Coast Intrastate Air Quality Control Region. 81.166 Section 81.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of Air Quality Control Regions § 81.166...

  6. Steelhead of the south-central/southern California coast: Population characterization for recovery planning

    USGS Publications Warehouse

    Boughton, David A.; Adams, P.B.; Anderson, E.; Fusaro, Craig; Keller, E.; Kelley, Elsie; Lentsch, Leo; Nielsen, J. L.; Perry, Katie; Regan, Helen; Swift, C.; Watson, Fred

    2006-01-01

    This report by the National Marine Fisheries Service applies a formal evaluation framework to the problem of delineating Oncorhynchus mykiss populations in the South-Central/Southern California Coast recovery domain, in support of recovery planning under the Endangered Species Act.

  7. Lateral continuity of the Blarney Creek Thrust, Doonerak Windown, Central Brooks Range, Alaska

    SciTech Connect

    Seidensticker, C.M.; Julian, F.E.; Phelps, J.C.; Oldow, J.S.; Avellemant, H.G.

    1985-04-01

    The contact between Carboniferous and lower Paleozoic rocks, exposed along the northern margin of the Doonerak window in the central Brooks Range, is a major thrust fault called the Blarney Creek thrust (BCT). The BCT has been traced over a distance of 25 km, from Falsoola Mountain to Wien Mountain. The tectonic nature of this contact is demonstrated by: (1) omission of stratigraphic units above and below the BCT; (2) large angular discordance in orientation of first-generation cleavage at the BCT; (3) numerous thrust imbricates developed in the upper-plate Carboniferous section that sole into the BCT; and (4) truncation of an upper-plate graben structure at the BCT. Lack of evidence for pre-Carboniferous deformation in the lower plate casts doubt on the interpretation of the contact as an angular unconformity. However, the localized presence below the BCT of Mississippian Kekiktuk Conglomerate and Kayak Shale, in apparent depositional contact with lower Paleozoic rocks, suggests that the BCT follows an originally disconformable contact between the Carboniferous and lower Paleozoic rocks. The juxtaposition of younger over older rocks at the BCT is explained by calling upon the BCT to act as the upper detachment surface of a duplex structure. Duplex development involves initial imbrication of the Carboniferous section using the BCT as a basal decollement, followed by formation of deeper thrusts in the lower Paleozoic section, which ramp up and merge into the BCT.

  8. Spiculitic chert reservoir in Glick Field, South-Central Kansas

    SciTech Connect

    Rogers, J.P.; Longman, M.W.; Lloyd, R.M.

    1995-01-01

    Glick Field, located in Kiowa and Comanche counties of southern Kansas, was discovered in 1957 and has produced more than 362 BCF from Mississippian Osage chert, commonly referred to as the {open_quotes}Chat.{close_quotes} Other {open_quotes}CHAT{close_quotes} reservoirs in Kansas and Oklahoma produce mainly from mixed chert and dolomite beneath the pre-Pennsylvanian unconformity, but Glick Field`s reservoir is dominated by chert containing abundant sponge spicules. Glick Field is a stratigraphic trap with production ending where the spiculitic facies pinches out into tight limestones to the south and west which provide a lateral seal. Additionally, updip, to the northeast, the productive facies is truncated by the unconformity. Reworked chert conglomerates overlying the spiculitic reservoir at the unconformity also produce some gas. The spiculitic chert forming the reservoir was desposited below storm wavebase and grades laterally in all directions into echinoderm and brachiopod-rich skeletal wackestones and lime mudstones. Even where completely silicified, these associated limestone are tight. Thus, the reservoir is an in situ oval-shaped complex of internally brecciated sponge mats and bioherms capped in part by the chert conglomerate. The spiculitic chert contains up to 50% porosity in molds after sponge spicules, matrix micropores and vugs are connected in part by fracture and breccia porosity. Distribution of the sponge bioherms which form the reservoir facies was partly controlled by a subtle change on the shallow Mississippian carbonate shelf from clean skeletal limestones southward into shaly (and probably more anoxic) carbonates known locally as the {open_quotes}Cowley Facies.{close_quotes} The sponge bioherms formed most commonly just updip from this boundary, which can be mapped across southern Kansas. Thus, lithologic mapping provides a potential exploration tool with which to find other stratigraphically trapped spiculitic reservoirs in the area.

  9. The 7-8 August 2008 eruption of Kasatochi Volcano, central Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, Christopher F.; Scott, William E.; Prejean, Stephanie G.; Schneider, David J.; Izbekov, Pavel; Nye, Christopher J.

    2010-12-01

    Kasatochi volcano in the central Aleutian Islands erupted unexpectedly on 7-8 August 2008. Kasatochi has received little study by volcanologists and has had no confirmed historical eruptions. The island is an important nesting area for seabirds and a long-term biological study site of the U.S. Fish and Wildlife Service. After a notably energetic preeruptive earthquake swarm, the volcano erupted violently in a series of explosive events beginning in the early afternoon of 7 August. Each event produced ash-gas plumes that reached 14-18 km above sea level. The volcanic plume contained large amounts of SO2 and was tracked around the globe by satellite observations. The cumulative volcanic cloud interfered with air travel across the North Pacific, causing many flight cancelations that affected thousands of travelers. Visits to the volcano in 2008-2009 indicated that the eruption generated pyroclastic flows and surges that swept all flanks of the island, accumulated several tens of meters of pyroclastic debris, and increased the diameter of the island by about 800 m. Pyroclastic flow deposits contain abundant accidental lithic debris derived from the inner walls of the Kasatochi crater. Juvenile material is crystal-rich silicic andesite that ranges from slightly pumiceous to frothy pumice. Fine-grained pyroclastic surge and fall deposits with accretionary lapilli cover the lithic-rich pyroclastic flow deposits and mark a change in eruptive style from episodic explosive activity to more continuous ash emission with smaller intermittent explosions. Pyroclastic deposits completely cover the island, but wave erosion and gully development on the flanks have begun to modify the surface mantle of volcanic deposits.

  10. Multiethnicity, pluralism, and migration in the south central Andes: An alternate path to state expansion

    PubMed Central

    Goldstein, Paul S.

    2015-01-01

    The south central Andes is known as a region of enduring multiethnic diversity, yet it is also the cradle of one the South America’s first successful expansive-state societies. Social structures that encouraged the maintenance of separate identities among coexistent ethnic groups may explain this apparent contradiction. Although the early expansion of the Tiwanaku state (A.D. 600–1000) is often interpreted according to a centralized model derived from Old World precedents, recent archaeological research suggests a reappraisal of the socio-political organization of Tiwanaku civilization, both for the diversity of social entities within its core region and for the multiple agencies behind its wider program of agropastoral colonization. Tiwanaku’s sociopolitical pluralism in both its homeland and colonies tempers some of archaeology’s global assumptions about the predominant role of centralized institutions in archaic states. PMID:26195732

  11. Multiethnicity, pluralism, and migration in the south central Andes: An alternate path to state expansion.

    PubMed

    Goldstein, Paul S

    2015-07-28

    The south central Andes is known as a region of enduring multiethnic diversity, yet it is also the cradle of one the South America's first successful expansive-state societies. Social structures that encouraged the maintenance of separate identities among coexistent ethnic groups may explain this apparent contradiction. Although the early expansion of the Tiwanaku state (A.D. 600-1000) is often interpreted according to a centralized model derived from Old World precedents, recent archaeological research suggests a reappraisal of the socio-political organization of Tiwanaku civilization, both for the diversity of social entities within its core region and for the multiple agencies behind its wider program of agropastoral colonization. Tiwanaku's sociopolitical pluralism in both its homeland and colonies tempers some of archaeology's global assumptions about the predominant role of centralized institutions in archaic states. PMID:26195732

  12. Alaska index; streamflow, lake levels, and water-quality records to September 30, 1988

    USGS Publications Warehouse

    Still, Patsy J.; Cosby, Jennie M.

    1989-01-01

    Streamflow, lake levels, and water quality data are compiled for stations in the southeast, south-central, southwest, Yukon basin , northwest, and Arctic Slope subregions of Alaska. The report includes a map of each hydrologic subregion and tables listing types of data collected and periods of records. (USGS)

  13. Stratigraphy, fossils, and age of sediments at the upper pit of the Lost Chicken gold mine: new information on the late Pliocene environment of east central Alaska

    NASA Astrophysics Data System (ADS)

    Matthews, John V., Jr.; Westgate, J. A.; Ovenden, Lynn; Carter, L. David; Fouch, Thomas

    2003-07-01

    The "upper pit" at the Lost Chicken placer gold mine in east central Alaska contains fossils that provide information on the flora and insect fauna of interior Alaska just before the onset of global cooling at 2.5 myr. Fossils come from sediments interbedded with the Lost Chicken tephra (dated at 2.9 ± 0.4 myr—early Late Pliocene) and portray the floodplain and valley of a small creek within a region dominated by a coniferous forest richer in genera and species than the present one. Climate was wetter and less continental, and there was probably little or no permafrost. At least one other Pliocene tephra (the Fortymile tephra) occurs at the site and is also associated with plant and insect fossils. Among these fossils are extinct plants and insects like those found at other Tertiary sites in northern Canada and Alaska. The Lost Chicken sequence is the same age as the Beaufort Formation on Meighen Island, more than 1000 km to the north. Like Lost Chicken, Meighen Island sediments contain fossils representing a diverse boreal environment. This shows that the latitudinal climate gradient during early Late Pliocene time was shallower than at present and the boreal forest had a far greater latitudinal span than now.

  14. Biological relationship between Central and South American Chibchan speaking populations: evidence from mtDNA.

    PubMed

    Melton, Phillip E; Briceño, I; Gómez, A; Devor, E J; Bernal, J E; Crawford, M H

    2007-05-01

    We examined mitochondrial DNA (mtDNA) haplogroup and haplotype diversity in 188 individuals from three Chibchan (Kogi, Arsario, and Ijka) populations and one Arawak (Wayuú) group from northeast Colombia to determine the biological relationship between lower Central American and northern South American Chibchan speakers. mtDNA haplogroups were obtained for all individuals and mtDNA HVS-I sequence data were obtained for 110 samples. Resulting sequence data were compared to 16 other Caribbean, South, and Central American populations using diversity measures, neutrality test statistics, sudden and spatial mismatch models, intermatch distributions, phylogenetic networks, and a multidimensional scaling plot. Our results demonstrate the existence of a shared maternal genetic structure between Central American Chibchan, Mayan populations and northern South American Chibchan-speakers. Additionally, these results suggest an expansion of Chibchan-speakers into South America associated with a shift in subsistence strategies because of changing ecological conditions that occurred in the region between 10,000-14,000 years before present. PMID:17340631

  15. Microclimate, Water Potential, Transpiration, and Bole Dielectric Constant of Coniferous and Deciduous Tree Species in the Continental Boreal Ecotone of Central Alaska

    NASA Technical Reports Server (NTRS)

    Zimmermann, R.; McDonald, K.; Way, J.; Oren, R.

    1994-01-01

    Tree canopy microclimate, xylem water flux and xylem dielectric constant have been monitored in situ since June 1993 in two adjacent natural forest stands in central Alaska. The deciduous stand represents a mature balsam poplar site on the Tanana River floodplain, while the coniferous stand consists of mature white spruce with some black spruce mixed in. During solstice in June and later in summer, diurnal changes of xylem water potential were measured to investigate the occurrence and magnitude of tree transpiration and dielectric constant changes in stems.

  16. Wandering terranes in southern Alaska: The Aleutia Microplate and implications for the Bering Sea

    NASA Astrophysics Data System (ADS)

    Marlow, Michael S.; Cooper, Alan K.

    1983-04-01

    Paleomagnetic and geological data suggest that much of southern Alaska is a collage of tectonostratigraphic terranes which originated in Mesozoic time at paleolatitudes far south of their present position. The time of `docking' of the terranes against cratonic Alaska is critical to defining their amalgamated size and extent during their northward motion as well as their role in the evolution of the Bering Sea. One of the largest of the tectonostratigraphic terranes, the Peninsular terrane of south central and southwestern Alaska, extends offshore along the outer Bering Sea continental margin (Beringia). Paleomagnetic data suggest that this terrane has moved northward through all of Cenozoic time, but geologic data imply that the terrane had accreted to Alaska by the end of the Mesozoic. In early Cenozoic time the eastern part of the Aleutian arc appears to have been superimposed on the Peninsular terrane, and postulated northward Cenozoic motion of the terrane would therefore have required northward motion of the arc. Two accretion models, based on docking times for terranes in Alaska, are proposed, and they illustrate that large areas of the abyssal Bering Sea, the Alaska Peninsula, the Aleutian arc, and the Beringian continental margin may be part of a superterrane or microplate called Aleutia (microplate as defined by Beck et al. (1980), i.e., a microplate is a displaced segment of lithosphere that has crustal roots, whereas a superterrane is an amalgamation of terranes which may or may not be rootless). Model A implies that the Aleutian arc developed in situ on the southern edge of Aleutia after the microplate had docked. In model B, the final docking time of the Peninsular terrane is late Cenozoic, which implies that the Aleutia microplate encompasses a mammoth area that includes parts of southern Alaska, the Alaska Peninsula, the southern Beringian margin, the abyssal Bering Sea (Kula plate), and the Aleutian arc. If model A is correct, the docking time of

  17. Early development of the south Central American margin: mechanisms and tectonic implications

    NASA Astrophysics Data System (ADS)

    Buchs, D. M.; Baumgartner, P. O.; Arculus, R.; Montes, C.; Bayona, G.; Cardona, A.

    2012-04-01

    The south Central American margin forms the SW border of the Caribbean Plate on top of the subducting Cocos and Nazca Plates between Nicaragua and Colombia. New and previous tectonostratigraphic, age and geochemical results show that the forearc basement between south Costa Rica and east Panama is composed of autochthonous and accreted sequences that provide important constraints on the development of the south Central American margin, the evolution of the Caribbean Plate and the formation of an inter-American land bridge. Autochtonous sequences in the forearc include three tectonostratigraphic units that occur at a regional scale: (1) a Late Cretaceous oceanic plateau considered to represent an extension of the Caribbean Large Igneous Province (CLIP) at the base of the arc; (2) Late Campanian to Maastrichtian protoarc sequences that cover or intrude the oceanic plateau; and (3) Maastrichtian to Eocene sequences of a more mature volcanic arc that overlies or intrude preceding units. These units clearly indicate that subduction initiation along the margin and, thus, the birth of the Caribbean Plate occurred in the Campanian. Incipient subduction was possibly triggered or facilitated by contrasted lithospheric strength across the edge of the CLIP and collision between the CLIP and South America during westward migration of South America. Accreted sequences in the forearc include mostly Late Cretaceous to Eocene seamount fragments between south Costa Rica and west Panama, with additional Eocene to Miocene olistostromal and hemipelagic sediments in south Costa Rica. The age and tectonostratigraphic relationships of accreted sequences, autochtonous sequences, and overlying forearc slope sediment suggest that subduction erosion, punctuated by local seamount or sediment accretion was the dominant process controlling the evolution of the outer margin at least until the Miocene. A major tectonic event affected the margin in the Middle Eocene, which is indicated by a

  18. Modeling the mass balance of the Wolverine Glacier Alaska USA using the PTAA model

    NASA Astrophysics Data System (ADS)

    Korn, D.

    2010-12-01

    Glaciers in Alaska have been increasingly losing mass over the last several decades. This trend is especially apparent in South-Central Alaska where many glaciers are undergoing rapid changes and contributing substantially to rising sea levels (Arendt et al., 2002). It is important to understand the rates at which these glaciers are losing mass as well as the important climatic drivers to better prepare for what the future holds in this region and the rest of the world. This work compares glacier mass balance data modeled through the Precipitation-Temperature Area Altitude (PTAA) mass balance model for the Wolverine Glacier in the Kenai Peninsula in South-Central Alaska to observed data from the USGS “benchmark” glacier program in order to help validate the model. The mass balance data are also correlated with climate data in order to understand the main climatic drivers of the glacier mass balance in this region.

  19. Can We Mitigate Climate Extremes using Managed Aquifer Recharge: Case Studies California Central Valley and South-Central Arizona, USA

    NASA Astrophysics Data System (ADS)

    Scanlon, B. R.; Reedy, R. C.; Faunt, C. C.; Pool, D. R.; Uhlman, K.

    2015-12-01

    Frequent long-term droughts interspersed with intense floods in the southwestern U.S. underscore the need to store more water to manage these climate extremes. Here we show how managed aquifer recharge can enhance drought resilience in the southwestern U.S. with ~ 70% of California under extreme drought and 75% of Arizona under moderate drought. Data on water sources, transportation, and users were compiled for managed aquifer recharge systems in the Central Valley and south-central Arizona. Groundwater depletion of 115 to 145 km3 in the 1900s created large subsurface reservoirs in thick alluvial basins in these regions. Large canals and aqueducts up to several 100 km long allow water to be imported from reservoirs, mostly in more humid regions. Imported water is either used instead of groundwater or is applied in surface spreading basins primarily during wet periods (≤1.3 km3/yr Central Valley, ≤0.7 km3/yr Arizona) and is extracted during droughts. The dominant water users include irrigators and municipalities both within and outside the managed aquifer recharge systems. Groundwater modeling indicates that recharge basins significantly increase groundwater storage in the Central Valley. Managed aquifer recharge systems significantly enhance drought resilience and increase sustainability of water resources in semiarid regions, complementing surface water reservoirs and conjunctive surface water/groundwater use by providing longer term storage.

  20. Gulf of Alaska, Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This MODIS true-color image shows the Gulf of Alaska and Kodiak Island, the partially snow-covered island in roughly the center of the image. Credit: Jacques Descloitres, MODIS Land Rapid Response Team

  1. Infectious Etiologies of Acute Febrile Illness among Patients Seeking Health Care in South-Central Cambodia

    PubMed Central

    Kasper, Matthew R.; Blair, Patrick J.; Touch, Sok; Sokhal, Buth; Yasuda, Chadwick Y.; Williams, Maya; Richards, Allen L.; Burgess, Timothy H.; Wierzba, Thomas F.; Putnam, Shannon D.

    2012-01-01

    The agents of human febrile illness can vary by region and country suggesting that diagnosis, treatment, and control programs need to be based on a methodical evaluation of area-specific etiologies. From December 2006 to December 2009, 9,997 individuals presenting with acute febrile illness at nine health care clinics in south-central Cambodia were enrolled in a study to elucidate the etiologies. Upon enrollment, respiratory specimens, whole blood, and serum were collected. Testing was performed for viral, bacterial, and parasitic pathogens. Etiologies were identified in 38.0% of patients. Influenza was the most frequent pathogen, followed by dengue, malaria, and bacterial pathogens isolated from blood culture. In addition, 3.5% of enrolled patients were infected with more than one pathogen. Our data provide the first systematic assessment of the etiologies of acute febrile illness in south-central Cambodia. Data from syndromic-based surveillance studies can help guide public health responses in developing nations. PMID:22302857

  2. Contextualizing the Trauma Experience of Women Immigrants From Central America, South America, and Mexico

    PubMed Central

    Kaltman, Stacey; de Mendoza, Alejandra Hurtado; Gonzales, Felisa A.; Serrano, Adriana; Guarnaccia, Peter J.

    2012-01-01

    Trauma has been understudied among Latina immigrants from Central and South America. This study examined the types and context of trauma exposure experienced by immigrant women from Central America, South America, and Mexico living in the United States. Twenty-eight women seeking care in primary care or social service settings completed life history interviews. The majority of the women reported some type of trauma exposure in their countries of origin, during immigration, and/or in the United States. In the interviews, we identified types of trauma important to the experience of these immigrants that are not queried by trauma assessments typically used in the United States. We also identified factors that are likely to amplify the impact of trauma exposure. The study highlights the importance of utilizing a contextualized approach when assessing trauma exposure among immigrant women. PMID:22144133

  3. Summer/winter stratification variability in the central part of the South Brazil Bight

    NASA Astrophysics Data System (ADS)

    Castro, Belmiro M.

    2014-10-01

    Analysis of the hydrographic data collected during seven consecutive high resolution summer/winter cruises in the central part of the South Brazil Bight off the coastal city of Ubatuba confirmed an observable summer/winter stratification variability of the shelf waters. The maximum bulk stratification occurred at mean distances of 85.6 km and 39.1 km from the coast in the austral winter and summer cruises, respectively. Estimates of the equivalent mixing power of the physical processes that increase or decrease the stratification in the inner and middle shelves showed that both shelf regions would be vertically well mixed were it not for buoyancy advection. In the inner shelf, buoyancy advection was associated with the along-shelf transport of low salinity waters originating from river runoff. In the middle shelf, buoyancy advection was due to the oceanic South Atlantic Central Water intrusions toward the coast.

  4. Genetic Diversity of the Ring-Tailed Lemur (Lemur catta) in South-Central Madagascar.

    PubMed

    Clarke, Tara A; Gray, Olivia; Gould, Lisa; Burrell, Andrew S

    2015-01-01

    Madagascar's lemurs, now deemed the most endangered group of mammals, represent the highest primate conservation priority in the world. Due to anthropogenic disturbances, an estimated 10% of Malagasy forest cover remains. The endangered Lemur catta is endemic to the southern regions of Madagascar and now occupies primarily fragmented forest habitats. We examined the influence of habitat fragmentation and isolation on the genetic diversity of L. catta across 3 different forest fragments in south-central Madagascar. Our analysis revealed moderate levels of genetic diversity. Genetic differentiation among the sites ranged from 0.05 to 0.11. These data suggest that the L. catta populations within south-central Madagascar have not yet lost significant genetic variation. However, due to ongoing anthropogenic threats faced by ring-tailed lemurs, continued conservation and research initiatives are imperative for long-term viability of the species. PMID:26022303

  5. Temperature changes derived from phenological and natural evidences in South Central China from 1850 to 2008

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Hua, Z.; Liu, Y.; Hao, Z.

    2015-08-01

    The annual temperature anomalies in South Central China from 1850 to 2008 were reconstructed by synthesizing three types of proxies: the spring phenodate of plants recorded in historical personal diaries and observations; the snowfall days extracted from historical archives and observed at meteorological stations; and five tree-ring width chronologies. The instrumental observation data and the leave-one-out method were used for calibration and validation. The results show that the temperature series in South Central China exhibits inter-annual and decadal fluctuations since 1850 (e.g., quasi-15 years and quasi-35 years fluctuations). The first three cold decades were the 1860s, 1890s and 1950s, while 1893 was the coldest year. Except that the three warm decades occurred around the 1850s, 1870s and 1960s, recent warm decades from the 1990s to the 2000s represent unprecedented warming since 1850.

  6. Temperature changes derived from phenological and natural evidence in South Central China from 1850 to 2008

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Hua, Z.; Liu, Y.; Hao, Z.

    2015-11-01

    Annual temperature anomalies in South Central China from 1850 to 2008 are reconstructed by synthesizing three types of proxies: spring phenodates of plants recorded in historical personal diaries and observations, snowfall days extracted from historical archives and observed at meteorological stations, and five tree-ring width chronologies. Instrumental observation data and the leave-one-out method are used for calibration and validation. The results show that the temperature series in South Central China exhibits interannual and decadal fluctuations since 1850. The first three cold decades were the 1860s, 1890s, and 1950s, while 1893 was very likely the coldest year. Except for the three warm decades that occurred around 1850, 1870, and 1960, along with the 1920s to the 1940s, the recent warm decades of the 1990s and 2000s represent unprecedented warming since 1850.

  7. 77 FR 76425 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Central...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ... specifications for Pacific cod included in the final 2012 harvest specifications for groundfish in the GOA (77 FR... groundfish in the GOA (77 FR 15194, March 14, 2012), after a 1,627 mt apportionment to the trawl catcher... to the pot and jig gear sectors (77 FR 67579, November 13, 2012). The Administrator, Alaska...

  8. Petroleum geology of Pacific margin of Central America and northern South America, from Guatemala to Ecuador

    SciTech Connect

    Scrutton, M.E.; Escalante, G.F.

    1986-07-01

    Exploration for hydrocarbons along the Pacific margin of Central America and northern South America has been limited and spasmodic. Less than 100 exploration wells have been drilled, with nearly 50 of these being in the Santa Elena, Progreso, and Guayas basins in Ecuador. Shows have been reported in some wells, and a few oil seeps are known. The only commercial production established to date has been from the Santa Elena Peninsula in Ecuador in the extreme south of the study area. Understanding of the geology in this part of the continental margin is incomplete at best. This paper reviews present-day knowledge in an attempt to define the sedimentary basins better, to characterize their structure and stratigraphy, and to assess their petroleum prospects. The area of continental margin reviewed is to the north, located northwest of the trench system where oceanic crust of the Cocos plate subducts under the Caribbean plate, and to the south, where the northern part of the Nazca plate collides with the South American plate. This plate tectonic setting forms the framework on which local structural and sedimentary events have created a series of relatively small trench-slope and forearc basins in what is now the coastal plain and adjacent offshore area of Central and South America, south or west of a line of mountain ranges with active volcanism. Sedimentary fill is generally of Tertiary age. The basins and subbasins recognized and described include: in Ecuador - Guayas, Santa Elena, Progreso, Valdivia, Bajo Grande, Manta, Muisne-Esmeraldas, and Borbon; in Colombia - Choco-Pacific; in Panama - Gulf of Panama basin complex (Santiago, Tonosi, Sambu), and Burica-Chiriqui; in Costa Rica - Terraba and Coronado/Tempisque; in Nicaragua - San Juan del Sur; and in the Honduras, El Salvador, and Guatemala - the Pacific coastal basin.

  9. Hydrocarbon potential of Cambrian-Ordovician Knox Group in south-central Kentucky

    SciTech Connect

    Gooding, P.J.

    1987-09-01

    In the eastern US, the carbonate rocks of the Cambrian-Ordovician Knox Group were deposited on a broad, gently sloping continental shelf in shallow hypersaline waters. A major unconformity occurs at the top of the Knox Group. This regional unconformity developed when the Sauk Sea retreated at the close of the Early Ordovician. In south-central Kentucky, the paleotopographic surface is characterized by extensive paleokarst developed on the upper Knox surface. The study area is located on the crest of the Cincinnati arch, a major structural feature that separates the Appalachian basin to the east from the Illinois basin on the west. Oil and gas are being produced from Cambrian-Ordovician rocks throughout the US, and south-central Kentucky is no exception. In south-central Kentucky, the Knox is of considerable economic importance. Hydrocarbon entrapment occurs at or near the unconformity at the top of the Knox. Approximately 3500 oil and gas wells and mineral exploration holes have penetrated the upper Knox Group in south-central Kentucky. Over 32 million bbl of oil have been recovered from 11 relatively shallow stratigraphic zones in 120 oil pools. These stratigraphic zones are generally encountered at depths of less than 2000 ft. A substantial amount of oil has been recovered from pools that produce exclusively from the Knox. Brecciated and fractured zones at the top of the Knox have also served as the host rock for sulfide mineralization, and these deposits may contain significant amounts of lead, zinc, and barium resources for future exploitation.

  10. Early Holocene basinal sediments of the Dakhleh Oasis region, south central Egypt

    NASA Astrophysics Data System (ADS)

    Brookes, Ian A.

    1989-09-01

    Twenty samples of artifactual ostrich eggshell and hearth charcoal, firmly to loosely associated with basinal lacustrine, playa, and sand sheet sediments in the Dakhleh Oasis region of south-central Egypt, yield radiocarbon ages between ca. 8800 and ca. 4700 yr B.P. The sediments record variable sedimentary responses to an early Holocene pluvial interval in this virtually rainless region. Differences of hydrogeology and morphometry among and within basin types complicate paleoclimatic interpretation.

  11. Crop identification and acreage estimation over large geographic areas using LANDSAT MSS data. [south central Kansas

    NASA Technical Reports Server (NTRS)

    Bauer, M. E. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. The comparison between the acreage estimates for the April LANDSAT data and the USDA Statistical Reporting Service estimates show no significant difference for the south central crop reporting district in Kansas. A paired-t test with an alpha = .05 was run comparing the percentages of wheat in each county. The results of their test showed no significant difference between the two estimates for wheat.

  12. A new Starlight Reserve for the central South Island of New Zealand

    NASA Astrophysics Data System (ADS)

    Hearnshaw, John

    2015-03-01

    The Aoraki Mackenzie International Dark Sky Reserve is a new reserve created in 2012 by the International Dark-Sky Association in the central South Island of New Zealand, and covers over 4300 square kilometres around Mt John University Observatory. It is the first such reserve to be recognized at gold tier level and is the largest dark sky reserve in the world. Astro-tourism in the new reserve will be a prominent activity in the coming years.

  13. Traditional use of medicinal plants in south-central Zimbabwe: review and perspectives

    PubMed Central

    2013-01-01

    Background Traditional medicine has remained as the most affordable and easily accessible source of treatment in the primary healthcare system of resource poor communities in Zimbabwe. The local people have a long history of traditional plant usage for medicinal purposes. Despite the increasing acceptance of traditional medicine in Zimbabwe, this rich indigenous knowledge is not adequately documented. Documentation of plants used as traditional medicines is needed so that the knowledge can be preserved and the utilized plants conserved and used sustainably. The primary objective of this paper is to summarize information on traditional uses of medicinal plants in south-central Zimbabwe, identifying research gaps and suggesting perspectives for future research. Methods This study is based on a review of the literature published in scientific journals, books, reports from national, regional and international organizations, theses, conference papers and other grey materials. Results A total of 93 medicinal plant species representing 41 families and 77 genera are used in south-central Zimbabwe. These plant species are used to treat 18 diseases and disorder categories, with the highest number of species used for gastro-intestinal disorders, followed by sexually transmitted infections, cold, cough and sore throat and gynaecological problems. Shrubs and trees (38% each) were the primary sources of medicinal plants, followed by herbs (21%) and climbers (3%). The therapeutic claims made on medicinal plants documented in south-central Zimbabwe are well supported by literature, with 82.8% of the plant species having similar applications in other regions of Zimbabwe as well as other parts of the world and 89.2% having documented biological and pharmacological properties. Conclusion This study illustrates the importance of traditional medicines in the treatment and management of human diseases and ailments in south-central Zimbabwe. Traditional medicines still play an important

  14. Holocene deposits of reservoir-quality sand along the Central South Carolina coastline

    SciTech Connect

    Sexton, W.J.; Hayes, M.O.

    1996-06-01

    The Holocene coastal sand deposits of the central South Carolina coastline were investigated to estimate volumes of reservoir-quality (RQ) sediments. These sand bodies, which vary considerably in size, thickness, shape, and continuity, were deposited in a variety of depositional settings including barrier islands, ebb-tidal deltas, exposed sand flats, tidal sand ridges, and tidal point bars. To identify the RQ sediment for each sand-body type, a conservative mud cutoff value of 15% was chosen. Average thickness values ranged from 6 m for barrier island deposits to 15 m for ebb-tidal deltas. Of the six most significant RQ sand depositional environments on the central portion of the South Carolina coast, ebb-tidal delta complexes accounted for 77% of all RQ sediments. This dominance of the ebb-tidal delta deposits is attributed to the relatively large tidal range in the area (up to 3 m) and to the presence of a number of large, incised alluvial valleys, which are host to estuarine complexes with large tidal prisms. If the Holocene sand deposits along the central 115 km of the South Carolina coast were preserved in the rock record, a total of 1.3 X 10{sup 6} ac-ft of RQ sands would be present, a significant amount considering the short time interval of approximately 5000 yr.

  15. The tobacco industry and secondhand smoke: lessons from Central and South America.

    PubMed

    Barnoya, Joaquin; Glantz, Stanton A

    2003-01-01

    For more than 20 years the tobacco industry has considered secondhand smoke to be a threat to its viability. In this article, we describe why secondhand smoke is important to tobacco control and how the tobacco industry's "Latin Project" sought to prevent the creation of smoke-free workplaces and public places in Central and South America. Eliminating secondhand smoke exposure not only reduces the risk of cardiovascular and other diseases, but also creates an environment that substantially reduces smoking and cigarette consumption among smokers. The "Latin Project" was initiated in 1991 by Philip Morris and British American Tobacco and managed by the law firm Covington & Burling. The project assembled a network of well-placed physicians and scientists to divert the attention away from secondhand smoke toward other indoor air pollutants. As proven in Central and South America, the tobacco industry has manipulated the secondhand smoke issue in order to avoid the development of smoke-free environments. Sub-Saharan Africa, facing an epidemiologic transition similar to the one experienced by Central and South America, should be aware of tobacco industry tactics. Further delay in implementing smoke-free environments will only increase the burden of cardiovascular disease in both areas of the world. PMID:13677420

  16. Tribal engagement strategy of the South Central Climate Science Center, 2014

    USGS Publications Warehouse

    Andrews, William J.; Taylor, April; Winton, Kimberly T.

    2014-01-01

    The South Central Climate Science Center was established by the U.S. Department of the Interior in 2012 to increase understanding of climate change and coordinate an effective response to climate-change effects on Native American tribes and natural and cultural resources that the Department manages. The eight regional Climate Science Centers of the U.S. Department of the Interior work closely with natural-resource management agencies, university researchers, and others such as tribes and private landowners on climate-change issues. The relatively large number of Native Americans in the south central United States and their special knowledge of changing ecosystems make working with tribes and tribal members on climate-change issues particularly important in this part of the Nation. This circular describes priorities of the South Central Climate Science Center and provides information about resources available from Climate Science Centers and partner agencies regarding climate change. The circular also describes how this Climate Science Center, tribes and tribal members, and others can collaborate to minimize potential harmful effects of climate change on human society and our surrounding ecosystems.

  17. Forest Fires Produce Dense Smoke over Alaska

    NASA Technical Reports Server (NTRS)

    2005-01-01

    On August 14, 2005, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this stunning image of forest fires raging across the width of Alaska. Smoke from scores of fires (marked in red) filled the state's broad central valley and poured out to sea. Hemmed in by mountains to the north and the south, the smoke spreads westward and spills out over the Bering and Chukchi Seas (image left). More than a hundred fires were burning across the state as of August 14. Air quality warnings have been issued for about 90 percent of the Interior, according to the August 12 report from the Alaska Department of Environmental Conservation's Division of Air Quality. Conditions have ranged from 'very unhealthy' to 'hazardous' over the weekend in many locations, including Fairbanks. A large area of high atmospheric pressure spread over much of the state, keeping temperatures high and reducing winds that would clear the air.

  18. Palaeomagnetism of lower cretaceous tuffs from Yukon-Kuskokwim delta region, western Alaska

    USGS Publications Warehouse

    Globerman, B.R.; Coe, R.S.; Hoare, J.M.; Decker, J.

    1983-01-01

    During the past decade, the prescient arguments1-3 for the allochthoneity of large portions of southern Alaska have been corroborated by detailed geological and palaeomagnetic studies in south-central Alaska 4-9 the Alaska Peninsula10, Kodiak Island11,12 and the Prince William Sound area13 (Fig. 1). These investigations have demonstrated sizeable northward displacements for rocks of late Palaeozoic, Mesozoic, and early Tertiary age in those regions, with northward motion at times culminating in collision of the allochthonous terranes against the backstop of 'nuclear' Alaska14,15. A fundamental question is which parts of Alaska underwent significantly less latitudinal translation relative to the 'stable' North American continent, thereby serving as the 'accretionary nucleus' into which the displaced 'microplates'16 were eventually incorporated17,18? Here we present new palaeomagnetic results from tuffs and associated volcaniclastic rocks of early Cretaceous age from the Yukon-Kuskokwin delta region in western Alaska. These rocks were probably overprinted during the Cretaceous long normal polarity interval, although a remagnetization event as recent as Palaeocene cannot be ruled out. This overprint direction is not appreciably discordant from the expected late Cretaceous direction for cratonal North America. The implied absence of appreciable northward displacement for this region is consistent with the general late Mesozoic-early Tertiary tectonic pattern for Alaska, based on more definitive studies: little to no poleward displacement for central Alaska, though substantially more northward drift for the 'southern Alaska terranes' (comprising Alaska Peninsula, Kodiak Island, Prince William Sound area, and Matunuska Valley) since late Cretaceous to Palaeocene time. ?? 1983 Nature Publishing Group.

  19. Prehistoric earthquakes on the Caribbean-South American plate boundary, central Range Fault, Trinidad

    USGS Publications Warehouse

    Prentice, Carol S.; Crosby, Christopher J.; Weber, John C.; Ragona, Daniel

    2010-01-01

    Recent geodetic studies suggest that the Central Range fault is the principal plate-boundary structure accommodating strike-slip motion between the Caribbean and South American plates. Our study shows that the fault forms a topographically prominent lineament in central Trinidad. Results from a paleoseismic investigation at a site where Holocene sediments have been deposited across the Central Range fault indicate that it ruptured the ground surface most recently between 2710 and 550 yr B.P. If the geodetic slip rate of 9–15 mm/yr is representative of Holocene slip rates, our paleoseismic data suggest that at least 4.9 m of potential slip may have accumulated on the fault and could be released during a future large earthquake (M > 7).

  20. Prehistoric earthquakes on the Caribbean-South American plate boundary, central range fault, Trinidad

    USGS Publications Warehouse

    Prentice, C.S.; Weber, J.C.; Crosby, C.J.; Ragona, D.

    2010-01-01

    Recent geodetic studies suggest that the Central Range fault is the principal plate-boundary structure accommodating strike-slip motion between the Caribbean and South American plates. Our study shows that the fault forms a topographically prominent lineament in central Trinidad. Results from a paleoseismic investigation at a site where Holocene sediments have been deposited across the Central Range fault indicate that it ruptured the ground surface most recently between 2710 and 550 yr B.P. If the geodetic slip rate of 9-15 mm/yr is representative of Holocene slip rates, our paleoseismic data suggest that at least 4.9 m of potential slip may have accumulated on the fault and could be released during a future large earthquake (M > 7). ?? 2010 Geological Society of America.

  1. The topographically asymmetrical Alaska Range: Multiple tectonic drivers through space and time

    NASA Astrophysics Data System (ADS)

    Benowitz, Jeffrey

    The topographically segmented, ˜700 km long Alaska Range evolved over the last ˜50 Ma in response to both far-field driving mechanisms and near-field boundary conditions. The eastern Alaska Range follows the curve of the Denali Fault strike-slip system, forming a large arc of high topography across southern Alaska. The majority of the topography in the eastern Alaska Range lies north of the Fault. A region of low topography separates the eastern Alaska Range from the central Alaska Range, where most of the high topography lies south of the Denali Fault. To the west, there is a restraining bend in the Fault. Southwest of the bend, the north-south trending western Alaska Range takes an abrupt 90 degree turn away from the Denali Fault. I applied 40Ar/39Ar thermochronology to over forty granitic samples to constrain the thermal history of the western and eastern Alaska Range. I combine the 40Ar/39Ar analyses with available apatite fission track and apatite (U-Th)/He dating. I then inferred the Alaska Range's exhumation history from the region's rates and patterns of rock cooling. Periods of mountain building within the Alaska Range are related to Paleocene-Eocene ridge subduction and an associated slab window (˜50 Ma to ˜35 Ma), Neogene flat-slab subduction of the Yakutat microplate (˜24 Ma to present), Yakutat microplate latitudinal variation in thickness (˜6 Ma to present), block rotation/migration, and fault reorganization along the Denali Fault. However, it is clear from basin, petrological and thermochronological constraints that not all of the far-field driving mechanisms affected every segment of the Alaska Range to the same degree or at the same time. Alaska Range tectonic reconstruction is also complicated by near-field structural controls on both the timing and extent of deformation. Fault geometry affects both the amount of exhumation (e.g., ˜14 km in the Susitna Glacier region of the eastern Alaska Range) and location of topographic development (e

  2. Compositional heterogeneity of central peaks within the South Pole-Aitken Basin

    NASA Astrophysics Data System (ADS)

    Moriarty, D. P.; Pieters, C. M.; Isaacson, P. J.

    2013-11-01

    high-spectral and -spatial resolution Moon Mineralogy Mapper data, we investigate compositional variations across the central peak structures of four impact craters within the South Pole-Aitken Basin (SPA). Two distinct causes of spectral diversity are observed. Spectral variations across the central peaks of Bhabha, Finsen, and Lyman are dominated by soil development, including the effects of space weathering and mixing with local materials. For these craters, the central peak structure is homogeneous in composition, although small compositional differences between the craters are observed. This group of craters is located within the estimated transient cavity of SPA, and their central uplifts exhibit similar mafic abundances. Therefore, it is plausible that they have all uplifted material associated with melts of the lower crust or upper mantle produced during the SPA impact. Compositional differences observed between the peaks of these craters reflect heterogeneities in the SPA subsurface, although the origin of this heterogeneity is uncertain. In contrast to these craters, Leeuwenhoek exhibits compositional heterogeneity across its central peak structure. The peak is areally dominated by feldspathic materials, interspersed with several smaller exposures exhibiting a mafic spectral signature. Leeuwenhoek is the largest crater included in the study and is located in a region of complex stratigraphy involving both crustal (feldspathic) and SPA (mafic melt and ejecta) materials. The compositional diversity observed in Leeuwenhoek's central peak indicates that kilometer-scale heterogeneities persist to depths of more than 10 km in this region.

  3. Deglaciation events in part of the Manchester South 7.5 degrees quadrangle south-central New Hampshire

    USGS Publications Warehouse

    Stone, Byron D.

    1971-01-01

    The study-area lies in south-central New Hampshire, and is bordered on the west by the Merrimack River, the principal north-south drainage route of central New Hampshire. The classical two tills of New England outcrop in the area. In a unique exposure of the sandy upper till, a loose ablation unit overlies a compact basal unit. Both upper till facies overlie a sheared section of dense, olive-gray lower till. Outwash sequences mapped in the study-area are progressively younger to the north, indicating backwastage of the Wisconsinan ice sheet. Primary structures in proglacial Lake Merrimack sediments include contorted bedding, buckled laminae, and folds. A large slumped section in lake sediments exhibits three distinct deformation zones, characterized by brittle, ductile, and unconsolidated deformation. Cross-cutting relationships establish four fold generations and a deformation sequence in the slumped section. Slip in each fold generation was along nearly parallel slip-lines, as deduced from analyses of fold rotation senses. The primary and slump deformation features contrast sharply with the intense style of deformation of lake beds below till at an apparent ice readvance cut. The deduced drag fold slip-line agrees with till fabric point maxima and dip-slip on one group of thrust faults. A southerly movement of readvancing ice is inferred. The study-area was deglaciated about 13,000 years ago, according to a proposed deglaciation model for New Hampshire. The model is based on Nye's theoretical glacier surface gradient, and evidence for active retreat of the Wisconsinan ice sheet.

  4. Distribution of planktonic cnidarians in response to South Atlantic Central Water intrusion in the South Brazilian Bight

    NASA Astrophysics Data System (ADS)

    Nogueira Júnior, Miodeli; Brandini, Frederico P.; Codina, Juan C. U.

    2014-10-01

    Five oceanographic cruises were made between November 2005 and June 2006, sampling a cross-shelf transect off the South Brazilian Bight (SBB; 26°46‧S) to follow the seasonal development of the South Atlantic Central Water (SACW) intrusion over the shelf and its influence on the assemblage of planktonic cnidarians. An onshore wind-driven bottom intrusion of the SACW was clearly perceptible, reaching the coast in January. From March onward, the SACW influence was gradually displaced seaward due to wind and tidal mixing. By late June the SACW influence was offshore and the inshore was dominated by low-salinity waters (<34.5). The abundance, distribution, and general taxonomic composition of both medusae and siphonophores were strongly influenced by the onshore intrusion of the SACW. An inshore-offshore gradient was clear. The Canonical Correspondence Analysis suggested that coastal species - dominated by Liriope tetraphylla, actinula larvae and Muggiaea kochi - were mostly related to food availability and a vertically mixed environment inshore, and their abundance and extent were reduced during intrusion periods. In contrast, species with offshore affinities tended to increase their abundance and distribution during intrusion periods, and were mostly related to the presence of thermal stratification and a deep chlorophyll maximum layer. Most of these offshore species, such as Aglaura hemistoma, Rhopalonema velatum and many calycophorans, are associated with the warm upper layer. However, high concentrations of large (>20 mm in diameter) Solmaris corona were observed exclusively in cold waters, suggesting this medusa is a SACW indicator.

  5. SURVEYS AND FIELD OBSERVATIONS OF HARMONIA AXYRIDIS AND OTHER COCCINELLIDAE (COLEOPTERA) IN EASTERN AND CENTRAL SOUTH DAKOTA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Harmonia axyridis, a coccinellid native to Asia, was discovered in South Dakota in 1996, but its distribution and habitat use in the state had remained undetermined. We sampled coccinellids from various habitats, including agricultural and natural areas, in eastern and central South Dakota in 2000 a...

  6. The Geodynamic Evolution of the Central and South East European Tethyan Chains

    NASA Astrophysics Data System (ADS)

    Sandulescu, M.

    2003-04-01

    Together with the Main Tethyan Suture Zone (disrupted fragments of the Tethyan oceanic domain ), built up of ophiolitic complexes and their overlying sedimentary sequences, three deformed continental margins (continental crust overlaped by tethyan sedimentary formations) may be recognized within the Central and South-East European area, i.g. the European, the Fore-Apulian and the Apulian margins. The Main Tethyan Suture Zone groups together the : Vardar Zone, South Pannonian-Insubric Suture, Transylvaniadian and Pienidian units. The European Margin cover the Northern and Eastern Carpathains, the South Carpathians,the Balkan, Rhodope and Serebo-Maceonein Massiv. To the Fore-Apulian microcontinent belogs the North Apuseni, Central West Carpathians and Austrialpine units, as well as the most important basement of the Pannonian Depression. Apulia covers the most important part of the Dinarides and Hellenides. The Tethyan Ocean opened, in the central and southern part of the area, during the Late Anisian or Early Ladinian and spread, with different rates since the early Upper Jurassic. The rifting which precede the opening may be Late Permian (?) and Lower Triassic. In the same time within the European Plate the intracontinental aulacogene north Dobrogea-South Crimea start to develop as a pull-apart basin connected with the southeasternmost segment of the Tornquist-Teisseyre Zone. In the northern part (West Carpathains and Alps) the Tethyan Ocean opened in the Middle Jurassic being a prolongation (?) of the Central Atlantic opening. The Bukk Terrane drifted since the end of the Lower Triasic from the Apulian Margin and collided the Fore-Apulian microcontinent until the earlly Jurassic. The first compressive events occur at the Jurassic/Cretaceous boundary stressed out by kalk-alkaline volcanics developed upon oceanic crust (Mariane-type subduction) and the “closing” of the North Dobrogea-South Crimea Aulacogene. Since the Middle Jurassic within the European

  7. Methane and Carbon Cioxide Emissions from 40 Lakes Along a North-South Latitudinal Transect in Alaska

    NASA Astrophysics Data System (ADS)

    Walter Anthony, K. M.; Sepulveda-Jauregui, A.; Anthony, P.; Grosse, G.; Chanton, J.

    2014-12-01

    We assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to physicochemical limnology, geographic characteristics and permafrost soil types and carbon stocks surrounding lakes. We found that all lakes were net sources of atmospheric CH4 and CO2 but that the climate warming impact of lake CH4 emissions was two times higher than that of CO2. Ebullition and Diffusion were the dominant modes of CH4 and CO2 emissions respectively. Geographically, CH4 emissions from stratified, dystrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes near Toolik Field Station and the rest of Alaska. Total CH4 emission was correlated with soil carbon stocks adjacent to lakes, concentrations of phosphate and total nitrogen in lake water, Secchi depth and lake area, with yedoma lakes having higher carbon stocks and nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.

  8. The tectonic development of south-central Asia and the paleogeographic setting of its hydrocarbon resources

    SciTech Connect

    Scotese, C.R. ); Tyrell, W.W. Jr. ); Maher, K.A. )

    1990-05-01

    The countries of south-central Asia (Afghanistan to Thailand) are made up of fragments of Gondwana that collided with the southern margin of Eurasia during the Mesozoic and Cenozoic. The Cimmerian terranes (Turkey, Iran, Afghanistan, Qiang Tang, and Burma-Malaya) rifted away from Gondwana beginning in the Late Carboniferous and were accreted to Asia during the Late Triassic-Jurassic. The Lhasa terrane, presumably also derived from Gondwana, was accreted during the Late Jurassic. By the Early Cretaceous, India-Madagascar had separated from Africa and from Australia-Antarctica. In the middle Cretaceous, India rapidly rifted away from Madagascar, and during the early Eocene collided with Asia giving rise to the Tibetam Plateau and the mountain belts from Afghanistan through Burma. The sedimentary basins and petroleum provinces adjacent to and south of these collision zones are best understood when viewed in the context of their tectonic history and paleogeographic setting. About 7 billion bbl of oil and 50 tcf of gas have been discovered in south-central Asia, mostly in Cenozoic deltaic sandstones or marine carbonate reservoirs in rift (Cambay), passive margin (Bombay shelf), and foreland basins (Assam, Indux, Potwar, Bengal) in India, Pakistan, and Bangladesh, and in a fore-arc setting in Burma. Source rocks are mostly Paleogene shale, but some Paleozoic and Mesozoic sources be present in Pakistan. New exploration is underway or will begin soon in India, Bangladesh, Nepal, and Burma.

  9. Large woody debris and salmonid habitat in the Anchor River basin, Alaska, following an extensive spruce beetle (Dendroctonus rufipennis) outbreak

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A widespread and intense spruce beetle outbreak has killed most of the mature white spruce trees across many watersheds in south-central Alaska. To investigate the potential habitat impacts in a salmon stream, we characterized the current abundance and species composition of large woody debris (LWD...

  10. Multi-resolution Changes in the Spatial Extent of Perennial Arctic Alpine Snow and Ice Fields with Potential Archaeological Significance in the Central Brooks Range, Alaska

    NASA Astrophysics Data System (ADS)

    Tedesche, M. E.; Freeburg, A. K.; Rasic, J. T.; Ciancibelli, C.; Fassnacht, S. R.

    2015-12-01

    Perennial snow and ice fields could be an important archaeological and paleoecological resource for Gates of the Arctic National Park and Preserve in the central Brooks Range mountains of Arctic Alaska. These features may have cultural significance, as prehistoric artifacts may be frozen within the snow and ice. Globally significant discoveries have been made recently as ancient artifacts and animal dung have been found in melting alpine snow and ice patches in the Southern Yukon and Northwest Territories in Canada, the Wrangell mountains in Alaska, as well as in other areas. These sites are melting rapidly, which results in quick decay of biological materials. The summer of 2015 saw historic lows in year round snow cover extent for most of Alaska. Twenty mid to high elevation sites, including eighteen perennial snow and ice fields, and two glaciers, were surveyed in July 2015 to quantify their areal extent. This survey was accomplished by using both low flying aircraft (helicopter), as well as with on the ground in-situ (by foot) measurements. By helicopter, visual surveys were conducted within tens of meters of the surface. Sites visited by foot were surveyed for extent of snow and ice coverage, melt water hydrologic parameters and chemistry, and initial estimates of depths and delineations between snow, firn, and ice. Imagery from both historic aerial photography and from 5m resolution IKONOS satellite information were correlated with the field data. Initial results indicate good agreement in permanent snow and ice cover between field surveyed data and the 1985 to 2011 Landsat imagery-based Northwest Alaska snow persistence map created by Macander et al. (2015). The most deviation between the Macander et al. model and the field surveyed results typically occurred as an overestimate of perennial extent on the steepest aspects. These differences are either a function of image classification or due to accelerated ablation rates in perennial snow and ice coverage

  11. Seismic hazard maps of Mexico, the Caribbean, and Central and South America

    USGS Publications Warehouse

    Tanner, J.G.; Shedlock, K.M.

    2004-01-01

    The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures due to an insufficient knowledge of existing seismic hazard and/or economic constraints. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. We have produced a suite of seismic hazard estimates for Mexico, the Caribbean, and Central and South America. One of the preliminary maps in this suite served as the basis for the Caribbean and Central and South America portion of the Global Seismic Hazard Map (GSHM) published in 1999, which depicted peak ground acceleration (pga) with a 10% chance of exceedance in 50 years for rock sites. Herein we present maps depicting pga and 0.2 and 1.0 s spectral accelerations (SA) with 50%, 10%, and 2% chances of exceedance in 50 years for rock sites. The seismicity catalog used in the generation of these maps adds 3 more years of data to those used to calculate the GSH Map. Different attenuation functions (consistent with those used to calculate the U.S. and Canadian maps) were used as well. These nine maps are designed to assist in global risk mitigation by providing a general seismic hazard framework and serving as a resource for any national or regional agency to help focus further detailed studies required for regional/local needs. The largest seismic hazard values in Mexico, the Caribbean, and Central and South America generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. High hazard values occur in areas where shallow-to-intermediate seismicity occurs frequently. ?? 2004 Elsevier B.V. All rights reserved.

  12. Seismic hazard maps of Mexico, the Caribbean, and Central and South America

    NASA Astrophysics Data System (ADS)

    Tanner, James G.; Shedlock, Kaye M.

    2004-10-01

    The growth of megacities in seismically active regions around the world often includes the construction of seismically unsafe buildings and infrastructures due to an insufficient knowledge of existing seismic hazard and/or economic constraints. Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. We have produced a suite of seismic hazard estimates for Mexico, the Caribbean, and Central and South America. One of the preliminary maps in this suite served as the basis for the Caribbean and Central and South America portion of the Global Seismic Hazard Map (GSHM) published in 1999, which depicted peak ground acceleration (pga) with a 10% chance of exceedance in 50 years for rock sites. Herein we present maps depicting pga and 0.2 and 1.0 s spectral accelerations (SA) with 50%, 10%, and 2% chances of exceedance in 50 years for rock sites. The seismicity catalog used in the generation of these maps adds 3 more years of data to those used to calculate the GSH Map. Different attenuation functions (consistent with those used to calculate the U.S. and Canadian maps) were used as well. These nine maps are designed to assist in global risk mitigation by providing a general seismic hazard framework and serving as a resource for any national or regional agency to help focus further detailed studies required for regional/local needs. The largest seismic hazard values in Mexico, the Caribbean, and Central and South America generally occur in areas that have been, or are likely to be, the sites of the largest plate boundary earthquakes. High hazard values occur in areas where shallow-to-intermediate seismicity occurs frequently.

  13. Molecular characterization of adenovirus circulating in Central and South America during the 2006–2008 period

    PubMed Central

    García, Josefina; Sovero, Merly; Laguna‐Torres, Victor Alberto; Gomez, Jorge; Chicaiza, Wilson; Barrantes, Melvin; Sanchez, Felix; Jimenez, Mirna; Comach, Guillermo; De Rivera, Ivette L.; Agudo, Roberto; Arango, Ana E.; Barboza, Alma; Aguayo, Nicolas; Kochel, Tadeusz J.

    2009-01-01

    Background  Human Adenoviruses are recognized pathogens, causing a broad spectrum of diseases. Serotype identification is critical for epidemiological surveillance, detection of new strains and understanding of HAdvs pathogenesis. Little data is available about HAdvs subtypes in Latin America. Methods  In this study, we have molecularly characterized 213 adenoviruses collected from ILI presenting patients, during 2006‐08, in Central and South America. Results  Our results indicate that 161(76%) adenoviruses belong to subgroup C, 45 (21%) to subgroup B and 7 (3%) to subtype E4. PMID:19903214

  14. Palynological and iridium anomalies at Cretaceous-Tertiary boundary, south-central Saskatchewan

    USGS Publications Warehouse

    Nichols, D.J.; Jarzen, D.M.; Orth, C.J.; Oliver, P.Q.

    1986-01-01

    The Cretaceous-Tertiary boundary in south-central Saskatchewan is marked by coincident anomalies in abundance of iridium and fern spores at the extinction level of a suite of Cretaceous pollen taxa. Evidence of disruption of the terrestrial flora includes the fern-spore abundance anomaly and local extinction of as much as 30 percent of angiosperm species. The reorganized earliest Tertiary flora is made up largely of surviving species that assumed new roles of dominance. Persistence of climatically sensitive taxa across the boundary indicates that if paleoclimate was altered by the terminal Cretaceous event, it returned quickly to the pre-event condition.

  15. Understanding the drivers of agricultural land use change in south-central Senegal

    USGS Publications Warehouse

    Wood, E. C.; Tappan, G. Gray; Hadj, Amadou

    2004-01-01

    Described is (1) the land use and land cover changes that have taken place in the Department of Velingara, an area of tropical dry woodland in south-central Senegal, (2) the biophysical and socio-economic drivers of those changes with an emphasis on transition to agricultural use, and (3) an assessment of the likelihood of intensification of agriculture in the Department. Results indicate that land devoted to agriculture, either in active cultivation or short-term fallow, is increasing. There is little evidence of agricultural intensification in most of Velingara, with extensification coming largely at the cost of reduction in both upland woodlands and riparian forest.

  16. Impacts of land use and climate change on carbon dynamics in south-central Senegal

    USGS Publications Warehouse

    Liu, Shu-Guang; Kaire, M.; Wood, Eric C.; Diallo, O.; Tieszen, Larry L.

    2004-01-01

    Total carbon stock in vegetation and soils was reduced 37% in south-central Senegal from 1900 to 2000. The decreasing trend will continue during the 21st century unless forest clearing is stopped, selective logging dramatically reduced, and climate change, if any, relatively small. Developing a sustainable fuelwood and charcoal production system could be the most feasible and significant carbon sequestration project in the region. If future climate changes dramatically as some models have predicted, cropland productivity will drop more than 65% around 2100, posing a serious threat to food security and the efficiency of carbon sequestration projects.

  17. Trace element content of leaves of desert shrubs in south-central Washington

    SciTech Connect

    Rickard, W.H.; Garland, T.R.

    1983-01-01

    Analyses of leaves of desert shrubs showed strong differences in macroelements according to species and location on the Arid Lands Ecology (ALE) site in south-central Washington. Halophytes were characterized by high levels of K, Cl, Br, Mn, and Na, and glycophytes by high levels of Ca and Mg. However, trace element content was not significantly different. Big sagebrush (Artemisia tridentata) leaves from Wyoming and the ALE site were not greatly different in trace element content. Natural leaf fall collections can be used to monitor changing levels of trace element content induced by coal combustion steam-electric plants.

  18. Diarrhea and respiratory symptoms among travelers to Asia, Africa, and South and Central America from Scotland.

    PubMed

    Redman, Christopher Allan; Maclennan, Alice; Wilson, Eleanor; Walker, Eric

    2006-01-01

    Surveillance using admissions to hospital, while being useful, is a poor indicator of the real incidence of disease encountered by travelers. An alternative is self-reported illness among those who attended at a pretravel clinic prior to their travels. Estimates of incidence and risk factors were determined for attendees at a travel clinic in Scotland using a questionnaire. Analysis for risk factors was carried out for those travelers visiting countries in Africa, Asia, or South and Central America, who had traveled for 1 week or more and had returned between 1997 and 2001 (N= 4,856). Multivariate logistic regression was used to test the hypotheses that time abroad and age-group would be significant for both respiratory and diarrheal symptoms regardless of which of the three geographical areas are visited. From 2006 returned questionnaires (response rate = 41.3%), diarrhea and respiratory symptoms were reported by 44.2 and 16.8% of respondents, respectively; the incidence was significantly greater among travelers to Asia for both diarrheal (55.5%) and respiratory (23.7%) symptoms than among travelers to Africa (36.6 and 12.2%, respectively) or South and Central America (39.5 and 16.2%, respectively). For diarrhea, age was a highly significant risk factor for travelers to Asia, South and Central America, and Africa. Being a self-organized tourist/backpacker, traveling to Asia was associated with increased risk, while for Africa and South and Central America visiting family or friends was associated with a lower risk. For travelers to Asia, traveling to the Indian subcontinent was significantly associated with increased risk. The majority of travelers had an adverse event while traveling abroad, with diarrhea and respiratory conditions being especially common despite attending a travel clinic for advice prior to departure. However, the limitations of this surveillance-based strategy have highlighted the requirement for more research to understand more fully the

  19. Unretrieved shooting loss of mourning doves in north-central South Carolina

    USGS Publications Warehouse

    Haas, G.H.

    1977-01-01

    Unretrieved loss for mourning doves (Zenaida macroura) in north-central South Carolina was between 27 and 41 percent of the retrieved kill for the 1973 through 1975 hunting seasons based on 1,396 doves shot by 281 hunters. Dove hunters hunted in groups, fired 8.6 shots per retrieved dove, and engaged in a substantial number of illegal activities. Increased dove populations and hunter bag resulted in increased unretrieved loss, numbers of shots per bagged bird, and illegal activities. Retriever dogs increased the efficiency of dove hunters.

  20. Escherichia Coli monitoring in the Spring Mill Lake watershed in south-central Indiana

    USGS Publications Warehouse

    Hasenmueller, N.R.; Comer, J.B.; Zamani, D.D.

    2003-01-01

    The escherichila (E) coli monitoring in the Spring Mill lake watershed in South-Central Indiana was presented. Water flowing from the springs in the park were analyzed to determine potential nonpoint-source contaminants entering Spring Mill Lake. E. Coli concentrations from the monitoring sites within the Spring Mill Lake watersheds varied greatly from concentrations below the detection limit, <1 most probable number (MPN) of organisms per 100 milliliters (mL) of water, to 980,000 MPN/100 mL. E. coli appears to be a potential health risk at several of the springs within the park, particularly at the Rubble site.

  1. Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

    DOE PAGESBeta

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K.; Greene, S.; Thalasso, F.

    2014-09-12

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to physicochemical limnology and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included Direct Ebullition, Diffusion, Storage flux, and a newly identified Ice-Bubble Storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lake CH4more » emissions was two times higher than that of CO2. Ebullition and Diffusion were the dominant modes of CH4 and CO2 emissions respectively. IBS, ~ 10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, dystrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. Total CH4 emission was correlated with concentrations of phosphate and total nitrogen in lake water, Secchi depth and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.« less

  2. Crustal Rheology and Rifted Margin Architecture: Comparing Iberia-Newfoundland, Central South Atlantic, and South China Sea

    NASA Astrophysics Data System (ADS)

    Brune, Sascha

    2015-04-01

    Crustal rheology controls the style of rifting and ultimately the architecture of rifted margins: Hot, weak, or thick continental crust is dominated by ductile deformation and extends symmetrically into a wide rift system. Extension in cold, strong, or thin crust is accommodated by brittle faults and ductile shear zones that facilitate narrow rifts with asymmetric fault geometries. This recipe provides the standard framework to understand 2D rift geometry, however, a variety of processes exert significant control on subsequent rift evolution and ultimately on the architecture of rifted margins: inherited structures, melting and volcanism, 3D effects, extension rate, and weakening mechanisms. Numerical forward modelling studies have the opportunity to evaluate the influence of these processes on rift evolution in order to understand the complex interaction between rheology and tectonic history of specific margins. Here I compare the formation of three different magma-poor margin pairs, Iberia-Newfoundland, the Central South Atlantic Rift Segment, and the South China Sea margins within a numerical forward modelling framework. I apply a 2D version of the finite element code SLIM3D, which includes nonlinear temperature- and stress-dependent elasto-visco-plastic rheology and is able to reproduces a wide range of rift-related deformation processes such as flexure, lower crustal flow, and faulting. The Iberia-Newfoundland rifted margins are marked by moderate crustal asymmetry, with ~70 km of hyper-extended crust (less than 10 km thick) on the Iberian side and a very narrow margin on the Newfoundland counterpart. Similar to the Iberia-Newfoundland conjugates, the Central South Atlantic margins are predominantly asymmetric, however involve a much stronger degree of asymmetry with more than 200 km of hyper-extended crust offshore Angola, but only few tens of km at the Brazilian side. Kinematic and numerical modelling suggests that the asymmetry is caused by lateral

  3. ISEA (International geodetic project in SouthEastern Alaska) for rapid uplifting caused by glacial retreat: (3) Absolute gravity measurements

    NASA Astrophysics Data System (ADS)

    Sun, W.; Miura, S.; Sato, T.; Kaufman, A. M.; Cross, R.; Freymueller, J. T.; Schiel, A.

    2006-12-01

    The southeast Alaska is undergoing a rapid ice-melting and land uplift due to the effect of global warming in the last three hundred years. The corresponding crustal deformation caused by the post-glacial rebound has been clearly detected by modern geodetic techniques, e.g., GPS and tidal gauge measurements (Larsen et al., 2004; Sato et al., 2005). The geodetic deformation provides us useful information in evaluating ice-melting rate, effect of global warming, and even the viscosity beneath the crust. For this purpose, however, integrated geodetic observation, especially including gravity measurement, is considered very important (Miura et al., a separate presentation at the same AGU conference; Wahr et al., 1995). Therefore, to detect the crutal deformation caused by the post-glacial rebound and to study the viscoelastic structure of the earth in the southeast Alaska, a joint team of Japanese and U.S. researchers has begun a three year project of GPS, earth tide, and absolute gravity measurements. In this presentation, results of the absolute gravity observation carried out between June 3 and June 18, 2006 are reported. During the 2006 observation campaign, a network of absolute gravity was for the first time established which is composed of five sites about 100 km around of Juneau: Bartlett Cove at Gustavus, Russell Island, Hains Fairground at Hains, UAS Egan Library at Juneau and Mendenhall Glacier Visitors Center at Juneau, Alaska. Absolute gravity data were acquired at the five sites using a Micro-LaCoste absolute gravimeter, serial number 111. A typical occupation recorded a set of 100 single measurements every half hour. At each site data were collected over a 48~62 hour period. Due to the bad ocean model in this area, ocean loading correction seems not efficient because large tidal residuals remain in the observed results. To carry out an accurate tidal correction, on site tidal observation was also performed. Detail discussions on tidal observation and

  4. ISEA (International geodetic project in SouthEastern Alaska) for rapid uplifting caused by glacial retreat: (4) Gravity tide observation

    NASA Astrophysics Data System (ADS)

    Sato, T.; Miura, S.; Sun, W.; Kaufman, A. M.; Cross, R.; Freymueller, J. T.; Heavner, M.

    2006-12-01

    The southeastern Alaska shows a large uplift rate as 30 mm/yr at most, which is considered to be closely related to the glacial isostatic adjustment (GIA) including two effects of the past and present-day ice melting (Larsen et al., 2004). So, this area is important to improve our knowledge of the viscoelastic property of the earth and to consider the global changes. Combing the displacement and gravity observations is useful to constrain the model computation results for GIA (Sato et al., 2006). In order to progress the previous work by the group of Univ. Alaska, Fairbanks (UAF), an observation project by Japan and USA groups was started in 2005 (Miura et al., this meeting). Under this project, June 2006, the continuous GPS measurements started (M. Kufman et al., this meeting) and the absolute gravity (AG) measurements were conducted (W. Sun et al., this meeting). Precise correction for the effect of ocean tide loading is one of the key to increase the observation accuracy of the GPS and gravity observations, especially for the AG measurement. Thanks for the satellite sea surface altimeters such as TOPEX/Poseidon and Jason-1, the accuracy of global ocean tide models based on these data has been much improved, and its accuracy is estimated at a level better than 1.3 cm as a RMS error of the vector differences of the 8 main tidal waves (Matsumoto et al., 2006). However, on the other hand, it is known that the southeastern Alaska is a place that shows a large discrepancy among the proposed global ocean tide models mainly due to a complex topography and bathymetry of the fjord area. In order to improve the accuracy of the ocean tide correction, we started the gravity tide observation at Juneau from June 2006. Two kinds of gravimeters are used for the observation. Sampling interval of the data is at every 1 min. We analyzed the 1 month data from the beginning of the observation and compared the tidal analysis results with the model tide including both effects of the

  5. Seismic Stratigraphy of the Central South China Sea Basin and Implications for Neotectonics

    NASA Astrophysics Data System (ADS)

    Li, C. F.; Ding, W.; Franke, D.; Yao, Y.; Pang, X.; Shi, H.; Li, J.; Cao, Y.

    2014-12-01

    International Ocean Discovery Program (IODP) Expedition 349 drilled five sites in the central South China Sea Basin. Three sites (U1431 in the East Subbasin, and U1433 and U1434 in the Southwest Subbasin) reached basalt interpreted to be igneous basement of the oceanic crust. Site U1435 on the northern continent-ocean boundary recovered pre-Oligocene sedimentary rocks deposited prior to the opening of the South China Sea. Furthermore, a full suite of geophysical logging was also carried out at Sites U1431 and U1433. These coring and logging data and physical property measurements are integrated with, and correlated to, regional reflection seismic data to map regional sequence stratigraphic boundaries and seismic facies of the central basin and the continent-ocean transition zone. With our carefully selected seismic profiles, stratigraphic correlation is possible even between the continent-ocean transition zone and the central basin, circumventing preexisting basement highs near the continent-ocean boundary that often prevent direct correlation. We interpret four sequence boundaries, which are Oligocene/Miocene, middle Miocene/late Miocene, Miocene/Pliocene, and Pliocene/Pleistocene boundaries. Seismic facies between sequence boundaries are often characteristic and distinctive, allowing relatively straightforward regional correlation. For example, massive Miocene carbonate deposits, if well consolidated, are readily distinguishable by strong seismic reflectivities, caused by their relatively higher density and velocity in contrast to those of interbedded turbidite clastic sediments. However, we found abrupt seismic facies changes both temporally and spatially. In particular, the fossil spreading ridge and the Zhongnan ridge between the East and Southwest Subbasins acted as major sedimentary barriers, across which seismic facies changes sharply and cannot be easily correlated. The well-constrained seismic sequence boundaries also allow us to estimate the timing of

  6. Structural and kinematic evolution of the Yukon-Tanana upland tectonites, east-central Alaska: A record of late Paleozoic to Mesozoic crustal assembly

    USGS Publications Warehouse

    Hansen, V.L.; Dusel-Bacon, C.

    1998-01-01

    The Yukon-Tanana terrane, the largest tectonostratigraphic terrane in the northern North American Cordillera, is polygenetic and not a single terrane. Lineated and foliated (L-S) tectonites, which characterize the Yukon-Tanana terrane, record multiple deformations and formed at different times. We document the polyphase history recorded by L-S tectonites within the Yukon-Tanana upland, east-central Alaska. These upland tectonites compose a heterogeneous assemblage of deformed igneous and metamorphic rocks that form the Alaskan part of what has been called the Yukon-Tanana composite terrane. We build on previous kinematic data and establish the three-dimensional architecture of the upland tectonites through kinematic and structural analysis of more than 250 oriented samples, including quartz c-axis fabric analysis of 39 samples. Through this study we distinguish allochthonous tectonites from parautochthonous tectonites within the Yukon-Tanana upland. The upland tectonites define a regionally coherent stacking order: from bottom to top, they are lower plate North American parautochthonous attenuated continental margin; continentally derived marginal-basin strata; and upper plate ocean-basin and island-arc rocks, including some continental basement rocks. We delineate three major deformation events in time, space, and structural level across the upland from the United States-Canada border to Fairbanks, Alaska: (1) pre-Early Jurassic (>212 Ma) northeast-directed, apparent margin-normal contraction that affected oceanic rocks; (2) late Early to early Middle Jurassic (>188-185 Ma) northwest-directed, apparent margin-parallel contraction and imbrication that resulted in juxtaposition of the allochthonous tectonites with parautochthonous continental rocks; and (3) Early Cretaceous (135-110 Ma) southeast-directed crustal extension that resulted in exposure of the structurally deepest, parautochthonous continental rocks. The oldest event represents deformation within a west

  7. Coordination and establishment of centralized facilities and services for the University of Alaska ERTS survey of the Alaskan environment

    NASA Technical Reports Server (NTRS)

    Belon, A. E. (Principal Investigator); Miller, J. M.

    1973-01-01

    The author has identified the following significant results. Scene 1072-21173 of the Anaktuvuk Pass region of the Brooks Range, Alaska, was studied from the point of view of a resource survey for purposes of land use planning as part of the effort to develop ERTS data processing and interpretation techniques. Other data sources and surface observations were utilized to produce a resource survey of a remote and undeveloped region of Alaska. Three vegetative types are apparent: moist tundra, low brush, and high brush. Watersheds are easily defined on the multispectral imagery. Features related indirectly to economic minerals are discernible from ERTS-1 imagery supported by ground truth data. These include mountains, outwash plains and alluvial deposits, drainage patterns, lineaments and probable bedding planes. This region falls within present land class categories which are not inconsistent with the imperatives of the resources. These land class categories include native village withdrawals, regional deficiency area, national interest study area for possible inclusion in a national system, public interest areas, utility corridor, and state land selection.

  8. Geologic map of the Alamosa 30’ × 60’ quadrangle, south-central Colorado

    USGS Publications Warehouse

    Thompson, Ren A.; Shroba, Ralph R.; Michael N. Machette; Fridrich, Christopher J.; Brandt, Theodore R.; Cosca, Michael A.

    2015-01-01

    The Alamosa 30'× 60' quadrangle is located in the central San Luis Basin of southern Colorado and is bisected by the Rio Grande. The Rio Grande has headwaters in the San Juan Mountains of Colorado and ultimately discharges into the Gulf of Mexico 3,000 kilometers (km) downstream. Alluvial floodplains and associated deposits of the Rio Grande and east-draining tributaries, La Jara Creek and Conejos River, occupy the north-central and northwestern part of the map area. Alluvial deposits of west-draining Rio Grande tributaries, Culebra and Costilla Creeks, bound the Costilla Plain in the south-central part of the map area. The San Luis Hills, a northeast-trending series of flat-topped mesas and hills, dominate the landscape in the central and southwestern part of the map and preserve fault-bound Neogene basin surfaces and deposits. The Precambrian-cored Sangre de Cristo Mountains rise to an elevation of nearly 4,300 meters (m), almost 2,000 m above the valley floor, in the eastern part of the map area. In total, the map area contains deposits that record surficial, tectonic, sedimentary, volcanic, magmatic, and metamorphic processes over the past 1.7 billion years.

  9. Combined Ice and Water Balances of Gulkana and Wolverine Glaciers, Alaska, and South Cascade Glacier, Washington, 1965 and 1966 Hydrologic Years

    USGS Publications Warehouse

    Meier, Mark Frederick; Tangborn, Wendell V.; Mayo, Lawrence R.; Post, Austin

    1971-01-01

    Glaciers occur in northwestern North America between lat 37 deg and 69 deg N. in two major mountain systems. The Pacific Mountain System, near the west coast, receives large amounts of precipitation, has very mild temperatures, and contains perhaps 90 percent of the glacier ice. The Rocky Mountain or Eastern System, on the other hand, receives nearly an order of magnitude less precipitation, has temperatures that range from subpolar to subtropic, and contains glaciers that are much smaller in both size and total area. As a contribution to the International Hydrological Decade program on combined balances at selected glaciers, the U.S. Geological Survey is conducting studies of ice and water balance on four glaciers in the Pacific Mountain System: Wolverine and Gulkana Glaciers in Alaska, South Cascade Glacier in Washington, and Maclure Glacier in California. Similar data are being collected by other organizations at five glaciers in western Canada, including two in the Rocky Mountain System, and at one glacier in the Rocky Mountain System in northern Alaska. Gulkana, Wolverine, South Cascade, and Maclure Glaciers have dissimilar mass balances, and each is fairly representative of the glaciers for its particular region. Gulkana Glacier (lat 63 deg 15' N., Alaska Range, Alaska) normally has an equilibrium line at an altitude of 1,800 m (meters), an activity index of about 6 mm/m (millimeters per meter), a winter balance of about 1.0 m, and an annual exchange of about 2.2 m. (Balance values are given in terms of water-equivalent measure; the winter balance of 1 m, for example, indicates a volume of ice equal in mass to a volume of water 1 m in depth covering the area of the glacier.) The normal approximate parameters for the other glaciers studied are as follows: Wolverine Glacier (lat 60 deg 24' N., Kenai Mountains, Alaska) - equilibrium-line altitude 1,200 m, activity index 9 mm/m, winter balance 2.5 m, and annual exchange 5.5 m; South Cascade Glacier (lat 48 deg 22

  10. A preliminary evaluation of regional ground-water flow in south-central Washington

    USGS Publications Warehouse

    La Sala, A. M., Jr.; Doty, G.C.; Pearson, F.J., Jr.

    1973-01-01

    The characteristics of regional ground-water flow were investigated in a 4,500-square-mile region of south-central Washington, centered on the U.S. Atomic Energy Commission Hanford Reservation. The investigation is part of the Commission's feasibility study on storing high-level radioactive waste in chambers mined in basaltic rocks at a. depth of about 3,000 feet or more below the surface. Ground-water flow., on a regional scale, occurs principally in the basalt and-in interbedded sediments of the Columbia River Group, and is controlled by topography, the structure of the basalt, and the large streams--the Columbia, Snake, and Yakima Rivers. The ground water beneath the main part of the Hanford Reservation, south and west of the Columbia River, inures southeastward from recharge areas in the uplands, including Cold Creek and Dry Creek valleys, and ultimately discharges to the Columbia River south of the reservation: East and southeast of the Columbia River, ground water flows generally southwestward and discharges to the River. The Yakima River valley contains a distinct flow system in which movement is toward the Yakima River from the topographic divides. A large southward-flowing ground-water system beneath the southern flank of the Horse Heaven Hills discharges to the Columbia River in the westward-trending reach downstream from Wallula Gap.

  11. Thickness variation of Simpson group in south-central Oklahoma and its tectonic significance

    SciTech Connect

    Islam, Q.T.; Crump, J. )

    1989-08-01

    The Middle Ordovician Simpson Group in the Southern Oklahoma aulacogen is composed of interbedded sandstone, limestone, and shale. Several pulses of subsidence controlled the deposition of these sediments. Simpson Group thickness variations, based on an isopach map and corresponding regional cross sections, define the presence of two distinct depositional basins flanked on their northern sides by a stable cratonic shelf. The anomalous thickness of Simpson sediments within these basins is related to syndepositional subsidence along zones of weakness initiated during the rifting stage of aulacogen development. The larger basin covers the western part of south-central Oklahoma. The northern flank of this basin illustrates a zone of rapid thickening of sediments. The updip portion of the northern flank is the northernmost limit of the Southern Oklahoma aulacogen. The depocenter of the larger basin is positioned in the Ardmore basin. Paleostress studies using calcite twin lamellae along the southeastern portion of the Sulfur fault within the smaller basin reveal an east-west compression followed by north-south compression. Surface folds formed by the east-west compression are highly faulted and overturned, whereas the folds formed by the north-south compression are open, slightly asymmetric, with rounded hinges and limbs. Similar east-west-trending structures in the subsurface could be a favorable target for hydrocarbon exploration. In general, these basins are genetically related but are separated by a large Precambrian basement block (Tishomingo Granite).

  12. Shale-filled channel system in Wilcox Group (Paleocene-Eocene), north-central south Louisiana

    SciTech Connect

    McCulloh, R.P.; Eversull, L.G.

    1986-09-01

    Anomalously thick shale intervals of limited extent within normally sandy facies of the Wilcox are evident on published regional electric log structure sections through south Louisiana. These intervals were investigated with a series of subregional stratigraphic electric log sections and by mapping. The stratigraphic sections show that in places the shale cuts out nearly 1000 ft (300 m) of adjacent interstratified sandstone and shale section and has lenticular, channel-like, cross-sectional geometry. The sections also indicate that the uppermost parts of the thick shale intervals are stratigraphically equivalent to, or at least contiguous with, a persistent subregional shale marker bed known informally as the Big Shale, but are distinguishable from it in places by more uniform log character. A map of the anomalously thick and uniform shale indicates a south-trending, relatively straight channel with a single bifurcation in southern Avoyelles Parish. The branches probably continue downdip, although they cannot be traced with confidence south of central St. Landry Parish because of the overall shalier Wilcox section and scarcity of adequately deep control wells. The channel shale is analogous to other early Cenozoic subsurface truncational shale masses that have been mostly interpreted as submarine canyon-channel fills. Stratigraphic trapping possibilities are evident from the truncation of bounding permeable units, but the possible continuation of the branches downdip suggests the potential for deep sandy equivalents and deep gas.

  13. Holocene coseismic and aseismic uplift of Isla Mocha, south-central Chile

    USGS Publications Warehouse

    Nelson, A.R.; Manley, W.F.

    1992-01-01

    During the past 6000 years Isla Mocha, a 12 km-long island 30 km off the coast of south-central Chile, experienced a 38 m fall of relative sea level caused primarily by rapid tectonic uplift of the island. As many as 18 raised shorelines (strandlines) record this uplift. Historic accounts of uplift during the great earthquakes (M > 8) of 1835 and 1960 suggest some of the more prominent prehistoric strandlines also emerged during great earthquakes on the interface between the Nazca and South America plates. But the close elevational spacing of strandlines, subdued morphology of strandline beaches, scarcity of exposed bedrock wave-cut platforms, and the extremely high rates of aseismic uplift (ca. 70 mm/yr) of the island since the last great earthquake suggest that many strandlines were raised by aseismic rather than coseismic uplift. Strandline heights and 14 new radiocarbon ages on marine shells show that the present-day uplift rate is more than three times the net rate (ca. 20 mm/yr) of the past 1000 years. The recent high rate probably reflects increased aseismic slip on an inferred thrust fault in the overriding South America plate. Isla Mocha overlies an area of high stress concentration between two major segments of the Chilean subduction zone. The inferred high rate of slip on the thrust fault may be a response to stress changes on the plate interface near the boundary between the segments. ?? 1992.

  14. Tectonics and depositional environments in early Pennsylvanian of south-central New Mexico

    SciTech Connect

    Kalesky, J. )

    1987-02-01

    The Pennsylvanian Magdalena Group unconformably overlies Precambrian to Mississippian strata throughout south-central New Mexico. Regional southward tilting, warping, and erosion resulted in progressively older pre-Pennsylvanian subcrop relations from south to north. Normal marine shelf sedimentation was represented by upward shoaling cycles containing mixed siliciclastics and carbonates. Channels cut into Ordovician strata in the southern Caballo Mountain area suggest that this area was a relatively deep valley or trough during Late Mississippian-Early Pennsylvanian erosion. Marine transgression from the south backfilled the preexisting stream valleys with sequences of packstone, wackestone, shale, and coarse quartzarenite. Topographically higher areas were blanketed with thin beds of laminated bioclastic packstone, grainstone, lime mudstone, and shale. Semirestricted tidal to nearshore environments are reflected in local sections by finely laminated hematitic dolomites, oncolitic wackestones, limestone conglomerates containing reworked Mississippian chert, and terrigenous shales supporting petrified wood float. Depositional onlap farther north resulted in a thinner and younger sequence. The cyclic nature of these deposits reflects a proximity to the shoreline and suggests an abruptly shifting base level, possibly controlled by Early Pennsylvanian glacial eustasy. The time-stratigraphic position of the valley-fill depositional unit may be broadly correlated to other Late Mississippian-Early Pennsylvanian valley-fill sequences recognized in the Delaware basin and Grand Canyon.

  15. Three-dimensional electrical resistivity image of the South-Central Chilean subduction zone

    NASA Astrophysics Data System (ADS)

    Kapinos, Gerhard; Montahaei, Mansoureh; Meqbel, Naser; Brasse, Heinrich

    2016-01-01

    Based on isotropic 3-D inversion, we re-interpret long-period magnetotelluric data collected across the geotectonic structures of the South-Central Chilean continental margin at latitudes 38°-41°S and summarize results of long-period magnetotelluric (MT) investigations performed between 2000 and 2005. The new 3-D conductivity image of the South-Central Chilean subduction zone basically confirms former 2-D inversion models along three profiles and complete the previous results. The models show good electrical conductors in the tip of the continental crustal beneath the Pacific Ocean, the frequently observed forearc conductor at mid-crustal levels, a highly-conductive zone at similar levels slightly offset from the volcanic arc and a - not well-resolved - conductor in the Argentinian backarc. The subducted Nazca Plate generally appears as a resistive but discontinuous feature. Unlike before, we are now able to resolve upper crustal conductors (interpreted as magma reservoirs) beneath active Lonquimay, Villarrica, and Llaima volcanoes which were obscured in 2-D inversion. Data fit is rather satisfactory but not perfect; we attribute this to large-scale crustal anisotropy particularly beneath the Coastal Cordillera, which we cannot include into our solution for the time being.

  16. Helicopter electromagnetic and magnetic geophysical survey data, Hunton anticline, south-central Oklahoma

    USGS Publications Warehouse

    Smith, Bruce D.; Smith, David V.; Deszcz-Pan, Maryla; Blome, Charles D.; Hill, Patricia

    2011-01-01

    This report is a digital data release for multiple geophysical surveys conducted in the Hunton anticline area of south-central Oklahoma. The helicopter electromagnetic and magnetic surveys were flown on March 16–17, 2007, in four areas of the Hunton anticline in south-central Oklahoma. The objective of this project is to improve the understanding of the geohydrologic framework of the Arbuckle-Simpson aquifer. The electromagnetic sensor for the helicopter electromagnetic survey consisted of six different transmitter-receiver orientations that measured the earth's electrical response at six distinct frequencies from approximately 500 Hertz to approximately 115,000 Hertz. The electromagnetic measurements were converted to electrical resistivity values, which were gridded and plotted on georeferenced maps. The map from each frequency represents a different depth of investigation for each area. The range of subsurface investigation is comparable to the depth of shallow groundwater. The four areas selected for the helicopter electromagnetic study, blocks A–D, have different geologic and hydrologic settings. Geophysical and hydrologic information from U.S. Geological Survey studies are being used by modelers and resource managers to develop groundwater resource plans for the Arbuckle-Simpson aquifer.

  17. Winter habitat associations of blackbirds and starlings wintering in the south-central United States

    USGS Publications Warehouse

    Matthew Strassburg; Crimmins, Shawn M.; George M. Linz; McKann, Patrick C.; Thogmartin, Wayne E.

    2015-01-01

    Birds can cause extensive crop damage in the United States. In some regions, depredating species comprise a substantial portion of the total avian population, emphasizing their importance both economically and ecologically. We used the National Audubon Society Christmas Bird Count data from the south-central United States and mixed-effects models to identify habitat factors associated with population trend and abundance for 5 species: red-winged blackbird (Agelaius phoeniceus), common grackle (Quiscalus quiscula), rusty blackbird (Euphagus carolinus), Brewer’s blackbird (Euphagus cyanocephalus), and European starling (Sturnus vulgaris). Overall, we found positive associations between bird abundance and agricultural land-cover for all species. Relationships between abundance and other land-cover types were species-specific, often with contrasting relationships among species. Likewise, we found no consistent patterns among abundance and climate. Of the 5 species, only red-winged blackbirds had a significant population trend in our study area, increasing annually by 2.4%. There was marginal evidence to suggest population increases for rusty blackbirds, whereas all other species showed no trend in population size within our study area. Our study provides managers who are interested in limiting crop damage in the south-central United States with novel information on habitat associations in the region that could be used to improve management and control actions.

  18. ISEA (International geodetic project in SouthEastern Alaska) for rapid uplifting caused by glacial retreat: (1) Outline of the project

    NASA Astrophysics Data System (ADS)

    Miura, S.; Sato, T.; Fujimoto, H.; Sun, W.; Freymueller, J. T.; Kaufman, A. M.; Cross, R.

    2006-12-01

    Glaciers at high latitudes are considered to be extremely sensitive to climate change and thus monitoring of glaciers is a clue to evaluate the future effect of global warming and the related phenomena. Ice mass changes also produce a time-variable surface load and give us useful data to investigate subsurface structure of the earth, especially to constrain the flow characteristics of the mantle. Larsen et al. (JGR03, GJI04, EPSL05) have extensively studied on vertical crustal movement in SE Alaska by means of raised shorelines, tide gauge measurements, and GPS to reveal the world's fastest glacial isostatic uplifting, which can be attributed to the response associated with glacier retreat. Displacement data, however, can only be used to constrain the sum of the elastic response to present-day ice melting (PDIM) and the viscoelastic one to past changes in ice. Wahr et al. (GRL95) proposed a method to distinguish the one from the other by combining surface displacement and absolute gravity measurements, though the approach may have limited spatial resolution. A Japan-US joint research project, ISEA (International geodetic research project in SouthEast Alaska), was initiated in 2005 to add new geodetic data sets and to refine the viscoelastic model derived by the previous studies. In June, 2006 three kinds of field work were carried out. Absolute gravity (AG) surveys (Sun et al., this meeting) were performed at five sites in and around Glacier Bay. Gravity tide (GT) observation using Scintrex's CG3M gravimeter was started in the campus of University of Alaska, Southeast (Sato et al., this meeting) to give precise corrections for the effect of ocean tide loading, which are the keys to increase the observation accuracy of AG and GPS,. Finally, new continuous GPS (CGPS) sites were established (Kaufman et al., this meeting) to examine not only the secular uplifting but the possible seasonal variation due to snow loading in the winter and ice loss in the summer. This

  19. Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

    DOE PAGESBeta

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K.; Greene, S.; Thalasso, F.

    2015-06-02

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to lakes' physicochemical properties and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included direct ebullition, diffusion, storage flux, and a newly identified ice-bubble storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lakemore » CH4 emissions was 2 times higher than that of CO2. Ebullition and diffusion were the dominant modes of CH4 and CO2 emissions, respectively. IBS, ~10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, mixotrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. The relationship between CO2 emissions and geographic parameters was weak, suggesting high variability among sources and sinks that regulate CO2 emissions (e.g., catchment waters, pH equilibrium). Total CH4 emission was correlated with concentrations of soluble reactive phosphorus and total nitrogen in lake water, Secchi depth, and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from

  20. Methane and carbon dioxide emissions from 40 lakes along a north-south latitudinal transect in Alaska

    NASA Astrophysics Data System (ADS)

    Sepulveda-Jauregui, A.; Anthony, K. M. Walter; Martinez-Cruz, K.; Greene, S.; Thalasso, F.

    2015-06-01

    Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH4) and carbon dioxide (CO2) emissions from northern lakes. Here we assessed the relationship between CH4 and CO2 emission modes in 40 lakes along a latitudinal transect in Alaska to lakes' physicochemical properties and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included direct ebullition, diffusion, storage flux, and a newly identified ice-bubble storage (IBS) flux. We found that all lakes were net sources of atmospheric CH4 and CO2, but the climate warming impact of lake CH4 emissions was 2 times higher than that of CO2. Ebullition and diffusion were the dominant modes of CH4 and CO2 emissions, respectively. IBS, ~10% of total annual CH4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH4 emissions from stratified, mixotrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. The relationship between CO2 emissions and geographic parameters was weak, suggesting high variability among sources and sinks that regulate CO2 emissions (e.g., catchment waters, pH equilibrium). Total CH4 emission was correlated with concentrations of soluble reactive phosphorus and total nitrogen in lake water, Secchi depth, and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing

  1. Age, Distribution, and Style of Deformation in Alaska North of 60°N: Implications for Assembly of Alaska

    NASA Astrophysics Data System (ADS)

    Moore, T. E.; Box, S. E.

    2015-12-01

    The structural architecture of Alaska is the product of a complex history of deformation along both the Cordilleran and Arctic margins of North America through interactions with ocean plates and with continental elements of Laurentia, Siberia, and Baltica. We use geological constraints to assign areal deformation to 14 time intervals and map their distributions in Alaska. Alaska can be divided into three domains with differing histories of deformation. The northern domain experienced the Early Cretaceous Brookian orogeny, an oceanic arc-continent collisional orogeny, followed by a mid-Cretaceous extensional overprint. Opening of the oceanic Canada Basin rifted the orogen from the Canadian Arctic margin, producing the bent trends of the orogen. The second domain constitutes the Phanerozoic Peninsular-Wrangellia-Alexander arc terrane and its paired Mesozoic accretionary prisms. Its structural history is unrelated to domains to the north until a shared history of Late Cretaceous deformation. The third domain, situated between the first two domains and roughly bounded by the Cenozoic dextral Denali and Tintina faults, includes the Yukon Composite terrane (Laurentian origin) and the large Farewell (Baltica origin) terrane. These terranes are not linked until Late Cretaceous sedimentary overlap, but we have not identified a shared deformation between these two terranes that might mark their juxtaposition by collisional processes. Similar early Late Cretaceous sedimentary linkages stitch the northern and central domains. Late Late Cretaceous folding and thrusting across much of Alaska south of the Brooks Range correlates temporally with the collision of the southern domain with the remainder of Alaska. Early Cenozoic shortening is mild across much of the state but is significant in the Brooks Range, and correlates in time with dextral faulting, ridge subduction, and rotation of western Alaska. Late Cenozoic shortening is significant in southern Alaska inboard of the

  2. The nature of the crust in the Yukon-Koyukuk province as inferred from the chemical and isotopic composition of five Late Cretaceous to Early Tertiary volcanic fields in western Alaska

    USGS Publications Warehouse

    Moll-Stalcup, E.; Arth, Joseph G.

    1989-01-01

    Late Cretaceous and early Tertiary volcanic and plutonic rocks in western Alaska comprise a vast magmatic province extending from the Alaska Range north to the Arctic Circle, south to Bristol Bay, and west to the Bering Sea Shelf. The chemical and isotopic composition of five of these Late Cretaceous to early Tertiary volcanic fields in the north central part of this province were studied to determine if Paleozoic or older continental crust underlies the Yukon-Koyukuk province. -from Authors

  3. A Storm-by-Storm Analysis of Alpine and Regional Precipitation Dynamics at the Mount Hunter Ice Core Site, Denali National Park, Central Alaska Range

    NASA Astrophysics Data System (ADS)

    Saylor, P. L.; Osterberg, E. C.; Kreutz, K. J.; Wake, C. P.; Winski, D.

    2014-12-01

    In May-June 2013, an NSF-funded team from Dartmouth College and the Universities of Maine and New Hampshire collected two 1000-year ice cores to bedrock from the summit plateau of Mount Hunter in Denali National Park, Alaska (62.940291, -151.087616, 3912 m). The snow accumulation record from these ice cores will provide key insight into late Holocene precipitation variability in central Alaska, and compliment existing precipitation paleorecords from the Mt. Logan and Eclipse ice cores in coastal SE Alaska. However, correct interpretation of the Mt. Hunter accumulation record requires an understanding of the relationships between regional meteorological events and micrometeorological conditions at the Mt. Hunter ice core collection site. Here we analyze a three-month window of snow accumulation and meteorological conditions recorded by an Automatic Weather Station (AWS) at the Mt. Hunter site during the summer of 2013. Snow accumulation events are identified in the Mt. Hunter AWS dataset, and compared on a storm-by-storm basis to AWS data collected from the adjacent Kahiltna glacier 2000 m lower in elevation, and to regional National Weather Service (NWS) station data. We also evaluate the synoptic conditions associated with each Mt. Hunter accumulation event using NWS surface maps, NCEP-NCAR Reanalysis data, and the NOAA HYSPLIT back trajectory model. We categorize each Mt. Hunter accumulation event as pure snow accumulation, drifting, or blowing snow events based on snow accumulation, wind speed and temperature data using the method of Knuth et al (2009). We analyze the frequency and duration of events within each accumulation regime, in addition to the overall contribution of each event to the snowpack. Preliminary findings indicate that a majority of Mt. Hunter accumulation events are of pure accumulation nature (55.5%) whereas drifting (28.6%) and blowing (15.4%) snow events play a secondary role. Our results will characterize the local accumulation dynamics on

  4. New Vitrinite Reflectance Data for the Bighorn Basin, North-Central Wyoming and South-Central Montana

    USGS Publications Warehouse

    Finn, Thomas M.; Pawlewicz, Mark J.

    2007-01-01

    Introduction The Bighorn Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 10,400 mi2 in north-central Wyoming and south-central Montana (fig. 1). Important conventional oil and gas resources have been discovered and produced from reservoirs ranging in age from Cambrian through Tertiary (Fox and Dolton, 1989, 1996a, b; De Bruin, 1993). In addition, a potential unconventional basin-centered gas accumulation may be present in Cretaceous reservoirs (Johnson and Finn, 1998; Johnson and others, 1999). The purpose of this report is to present new vitrinite reflectance data to be used in support of the U.S Geological Survey's assessment of undiscovered oil and gas resources of the Bighorn Basin. These new data supplement previously published data by Nuccio and Finn (1998), and Yin (1997), and lead to a better understanding and characterization of the thermal maturation and burial history of potential source rocks. Eighty-nine samples of Cretaceous and Tertiary strata (fig. 2) were collected and analyzed - 15 samples were from outcrops around the margins of the basin and 74 samples were well cuttings (fig. 1). Forty-one of the samples were shale, two were carbonaceous shale, and the remainder from coal. All samples were analyzed by vitrinite reflectance to determine levels of thermal maturation. Preparation of samples for reflectance analysis required (1) crushing the larger pieces into 0.25-to 1-mm pieces, (2) casting the pieces with epoxy in pre-cut and drilled plugs, and (3) curing the samples overnight. Subsequently, a four-step grinding and polishing process was implemented that included sanding with progressively finer sandpaper (60 and 600 grit) followed with a two-step polishing process (0.3 and 0.05 micron). Vitrinite reflectance measurements were determined at 500 X magnification using plane-polarized incident white light and a 546-nm monochromatic filter in immersion oil. For samples containing

  5. South-Central Tibetan Seismicity from HiCLIMB Seismic Array Data

    NASA Astrophysics Data System (ADS)

    Carpenter, S.; Nabelek, J.; Braunmiller, J.

    2010-12-01

    The HiCLIMB broadband passive seismic experiment (2002-2005) operated 233 sites along a 800-km long north-south array extending from the Himalayan foreland into the Central Tibetan Plateau and a flanking 350x350 km lateral array in southern Tibet and eastern Nepal. We use data from the experiment’s second phase (June 2004 to August 2005), when stations operated in Tibet, to locate earthquakes in south-central Tibet, a region with no permanent seismic network where little is known about its seismicity. We used the Antelope software for automatic detection and arrival time picking, event-arrival association and event location. Requiring a low detection and event association threshold initially resulted in ~110,000 declared events. The large database size rendered manual inspection unfeasible and we developed automated post-processing modules to weed out spurious detections and erroneous phase and event associations, which stemmed, e.g., from multiple coincident earthquakes within the array or misplaced seismicity from the great 2004 Sumatra earthquake. The resulting database contains ~32,000 events within 5° distance from the closest station. We consider ~7,600 events defined by more than 30 P and S arrivals well located and discuss them here. Seismicity in the subset correlates well with mapped faults and structures seen on satellite imagery attesting to high location quality. This is confirmed by non-systematic, kilometer-scale differences between automatic and manual locations for selected events. Seismicity in south-central Tibet is intense north of the Yarlung-Tsangpo Suture. Almost 90% of events occurred in the Lhasa Terrane mainly along north-south trending rifts. Vigorous activity (>4,800 events) accompanied two M>6 earthquakes in the Payang Basin (84°E), ~100 km west of the linear array. The Tangra-Yum Co (86.5°E) and Pumqu-Xianza (88°E) rifts were very active (~1,000 events) without dominant main shocks indicating swarm like-behavior possibly related

  6. Evaluation of PARIS performance in the South Central Coast Air Basin. Volume 2. Technical report. Final report

    SciTech Connect

    Douglas, S.G.; Daly, C.; Moore, G.E.; Myers, T.C.

    1991-12-01

    The primary goal of the study was to compare PARIS model performance in simulating ozone in the South Central Coast Air Basin (SCCAB) for 22-24 September 1985 using alternative wind fields. One wind field was generated by the Diagnostic Wind Model (DWM), and the other by the Colorado State University Mesoscale Model (CSUMM). The overall objective of the South Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP) project was to develop a means of assessing the aggregate impact of offshore petroleum industry sources on onshore ozone (O3) and nitrogen dioxide (NO2) concentrations.

  7. Evaluation of PARIS performance in the South Central Coast Air Basin. Volume 1. Executive Summary. Final report

    SciTech Connect

    Douglas, S.G.; Daly, C.; Moore, G.E.; Myers, T.C.

    1991-12-01

    The primary goal of the study was to compare PARIS model performance in simulating ozone in the South Central Coast Air Basin (SCCAB) for 22-24 September 1985 using alternative wind fields. One wind field was generated by the Diagnostic Wind Model (DWM), and the other by the Colorado State University Mesoscale Model (CSUMM). The overall objective of the South Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP) project was to develop a means of assessing the aggregate impact of offshore petroleum industry sources on onshore ozone (O3) and nitrogen dioxide (NO2) concentrations.

  8. The Protective Effects of Adolescent Motherhood in South Central Appalachia: Salvation From Drugs and Emptiness.

    PubMed

    Dalton, Elizabeth D

    2015-09-01

    This study qualitatively explored the meaning of teenage motherhood to young Appalachian mothers. Fourteen in-depth interviews at the homes of mothers between the ages of 18 and 22 from the South Central Appalachian region were conducted. Findings indicate that teenage motherhood is symbolically reproduced by filling a void and providing escape from the drug culture. Analysis of these findings indicates that the meaning of motherhood is characterized by salvation. This salvation is shaped by the emotional chasm that motherhood fills, as well as the protective barrier it provides between the mother and the surrounding drug culture. Implications of these findings might include a need to examine the protective effects of motherhood from negative sociocultural forces among other subcultures. Also, the pervasive drug culture that surrounds young people in Appalachia should be taken into consideration when shaping policy and interventions for teenage pregnancy prevention. PMID:24817205

  9. Ground-water resources of the St. James area, South-central Minnesota

    USGS Publications Warehouse

    Ropes, L.H.

    1969-01-01

    The purpose of this investigation was to evaluate the quality and quantity of the ground-water resources in the area of St. James, Minnesota. St. James is located in the center of Watonwan County in south-central Minnesota. The area is covered by a thick layer of glacial drift which is underlain by Cretaceous, Cambrian, and Precambrian rocks. St. James presently obtains its water supply from two aquifers. One is a Cretaceous sandstone 160 feet below the surface, in which two wells are completed. This aquifer yields abundant water but it is of poor quality and is expensive to treat. The second source, tapped by three municipal wells, is a surficial sand and gravel deposit less than 40 feet thick at the well field. This aquifer produces water of better quality, but its extent and capacity are not known. There are other wells in the area completed at depths ranging from 15 to 500 feet.

  10. Digital data from the Great Sand Dunes airborne gravity gradient survey, south-central Colorado

    USGS Publications Warehouse

    Drenth, B.J.; Abraham, J.D.; Grauch, V.J.S.; Labson, V.F.; Hodges, G.

    2013-01-01

    This report contains digital data and supporting explanatory files describing data types, data formats, and survey procedures for a high-resolution airborne gravity gradient (AGG) survey at Great Sand Dunes National Park, Alamosa and Saguache Counties, south-central Colorado. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve. The data described were collected from a high-resolution AGG survey flown in February 2012, by Fugro Airborne Surveys Corp., on contract to the U.S. Geological Survey. Scientific objectives of the AGG survey are to investigate the subsurface structural framework that may influence groundwater hydrology and seismic hazards, and to investigate AGG methods and resolution using different flight specifications. Funding was provided by an airborne geophysics training program of the U.S. Department of Defense's Task Force for Business & Stability Operations.

  11. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1986

    SciTech Connect

    Wiman, W.D.

    1987-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1986 was considerably reduced compared to 1985. Brazil, Colombia, Ecuador, Guatemala, and Venezuela had increased oil production, with Colombia showing a dramatic 71% increase attributed mainly to bringing on-stream the pipeline connecting Occidental-Shell-Ecopetrol's Cano Limon complex to the port of Covenas. Significant discoveries were reported from Argentina in the Olmedo, Oran, and San Jorge basins; Brazil in the offshore Campos and Amazon basins; Colombia in the Llanos basin; Ecuador in the Oriente basin; Mexico in the Bay of Campeche; Peru in the Ucayali basin; and Venezuela in the Eastern Venezuela basin. Eastern Venezuela's Furrial discovery is reported to have recoverable reserves of more than 1 million bbl of oil, and Shell's Ucayali basin discovery is reported to hold more than 7 tcf of gas. 7 figures, 10 tables.

  12. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1985

    SciTech Connect

    Wiman, W.D.

    1986-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1985 was concentrated in proven petroleum provinces. Successful exploration and development efforts were most intense in Colombia and Venezuela, where activity centered around the Cano Limon field area. Initial production of 30,000 BOPD from Cano Limon started in December, raising Colombia again to the ranks of an exporting nation. Another significant discovery in Colombia was San Francisco field in the Upper Magdalena basin. Argentina reported significant discoveries by YPF in the Northwest Cretaceous and Neuquen basins and by Total offshore Tierra del Fuego. Brazil continued to discover major reserves in the offshore Campos basin in ever-increasing water depths. At year end, Venezuela was drilling Furrial-1 in eastern Venezuela. The well is reported to be the outstanding discovery of 1985, if not of the last 2 decades. 4 figures, 7 tables.

  13. Seismic structure in central Mexico: Possible fragmentation of the subducted South Cocos plate

    NASA Astrophysics Data System (ADS)

    Dougherty, S. L.; Clayton, R. W.

    2012-12-01

    The fine-scale seismic structure of the central Mexico subduction zone is studied using moderate-sized (M4-6) intraslab earthquakes. Regional waveforms from the Meso America Subduction Experiment (MASE), Veracruz-Oaxaca (VEOX), and Servicio Sismológico Nacional (SSN) seismic arrays are complicated and contain detailed information about the subduction zone structure, including evidence of lateral heterogeneity. This waveform information is used to model the structure of the subducted plate, particularly along the transition from flat to normal subduction located to the east of the MASE array. Based on the results of plate motion studies showing that the Cocos plate moves differently on either side of the Orozco Fracture Zone (OFZ) coupled with our own structural modeling results across the flat-to-normal slab transition west of the MASE array, we recently proposed that the Cocos slab is currently fragmenting into a North Cocos plate and a South Cocos plate along the eastern projection of the OFZ. In the east, observations of a sudden change in slab dip combined with the abrupt end of the Trans Mexican Volcanic Belt suggest a second possible slab tear located within the South Cocos plate. The eastern lateral extent of a thin ultra-slow velocity layer (USL) imaged atop the Cocos slab in recent studies along the MASE array is examined here using MASE, VEOX, and SSN waveforms to test if the USL ends along a lineament related to the potential slab tear. We observe changes in waveform complexity across the sharp transition in slab dip, which may indicate a possible tear in the South Cocos plate. We perform 1D and 2D waveform modeling in order to image the structure of the slab and overriding plate in this region. The tears could indicate a slab rollback mechanism in which separate slab segments move independently.

  14. Tectonic geomorphology of the south-central Appalachians: The influence of Triassic extension

    SciTech Connect

    Webb, J.A. . Geology Dept.); Henika, W.S. . Division of Mineral Resources)

    1994-03-01

    During the final phase of the Alleghanian Orogeny, which ended probably in the mid-Permian, intense thrusting created a high mountain range with relief of up to 4.5 km and a width of 250--300 km. The drainage divide presumably lay within the Piedmont or Blue ridge Provinces, and probably ran subparallel to the present-day mid-Atlantic coastline. In the Middle and Late Triassic this mountain range was disrupted by the initial phases of rifting between the African and North American Plates. Many of the Alleghanian thrusts were reactivated as listric normal faults, creating a series of long, narrow asymmetric half grabens, and resulting in extensive delamination and thinning of the crust, particularly in the eastern Piedmont. South of the Salisbury Embayment the western limit of the Triassic basins steps consistently eastward, mirroring the offset of the ocean floor anomalies south of the Bermuda Fault Zone. The offset is also reflected by the easterly displacement of the present-day Appalachian drainage divide in southern virginia. This strongly suggests that the divide is largely inherited from the Triassic faulting episode. Rivers flowing westwards from the present-day Appalachians, including those like the New River crossing the Valley and Ridge Province, have retained more or less their pre-Triassic orientation, when they flowed down the western flanks of the Alleghanian mountains. The Triassic basins were separated by coast-parallel ranges with as much as 1 km of relief; these were largely eroded in the mid-Jurassic, so that by the Early Cretaceous the south-central Appalachians had more or less their present appearance. Subsequent erosion has probably resulted in westward retreat of the drainage divide.

  15. Spatial and temporal interactions between livestock and wildlife in South Central Spain assessed by camera traps.

    PubMed

    Kukielka, E; Barasona, J A; Cowie, C E; Drewe, J A; Gortazar, C; Cotarelo, I; Vicente, J

    2013-11-01

    The diversification of livestock farms into hunting estates in South Central Spain (SCS) may impede the success of Mycobacterium bovis eradication programmes by facilitating transmission between wildlife and livestock. In this observational study we aimed to provide information of relevance about the nature and frequency of interactions (observed visits to study points) between livestock (cattle and domestic pigs) and wildlife (wild boar and red deer). The study was conducted in an extensive cattle farm in SCS where the land is also used for game hunting. During a period of one year, camera traps (n=16) were placed at a priori risk points for interspecies interactions: water (natural and artificial troughs), food placed on the ground for baiting wildlife, and pasture. To define indirect interspecies interactions, a critical time window for M. bovis to survive in the environment was selected based on the literature. Results suggest that wildlife frequented food and pasture points more often than water points, and that the number of visits increased through the dry season, peaking during the acorn season (October-January) and the deer breeding season (June-July). Direct interactions were rare (n=10), as opposed to indirect interactions (n=8992). Wildlife-followed-by-livestock interactions (n=7714) occurred much more often than livestock-followed-by-wildlife (n=1278) and were frequent at water points (66% water points, 17% food, 17% pasture). Results also suggest that water points are a hotspot for indirect interactions and might therefore be a source of infection at the wildlife-livestock interface in the territory covered, particularly for M. bovis, as it is around water where the bacteria seem to survive the longest. Preventing aggregation and therefore reducing contact rates between domestic and wild animals especially at water points may be valuable for disease control in South Central Spain. PMID:24050782

  16. Transmission losses during two flood events in the Platte River, south-central Nebraska

    NASA Astrophysics Data System (ADS)

    Huang, Yuanyang; Chen, Xunhong; Chen, Xi; Ou, Gengxin

    2015-01-01

    The Platte River in south-central Nebraska is a priority reach to maintain appropriate in-stream flow for healthy stream habitat. Transmission losses normally take place here when flood wave or reservoir-release water travels through during summer and fall. However, it is found that the reservoir-release water hardly arrived at the habitat area due to the transmission losses. Meanwhile, the limited reservoir water also is critical for crop irrigations during the same season. Therefore, to reconcile the water requirement conflict, the knowledge of the temporal-spatial variations of the transmission losses along the river is necessary to better manage the released water. Two flood events, which were only generated by upstream rainstorms, traveled through the nearly non-flowing reach of the Platte River in south-central Nebraska during the summer of 2013. The hydrological records during the two flood events provided unique data sets to study the transmission losses in the reach. The objective of this study was to investigate the temporal-spatial variation of the transmission losses during the two flood events in the reach. A numerical-analytical transmission loss model was developed to support the analysis. The results indicated that the transmission loss process in the study reach would be reasonably simulated using an effective aquifer transmissivity value of 2000 m2/d and an effective stream leakance value of 600 1/d. About 52% and 21% of the stream water flowed into the reach became the transmission losses during the two flood events, respectively. The transmission losses significantly enhanced the stream stage attenuation during the two events. Due to the stream stage attenuation, the total transmission losses decreased linearly between the upstream and downstream gauges, but its detailed spatial variation can be documented based on further hydrogeological data collection along the reach.

  17. Watershed Governance in South-Central Texas: Working from the Bottom up

    NASA Astrophysics Data System (ADS)

    Lopes, V. L.

    2014-12-01

    The purpose of this presentation is to introduce a set of key concepts that can guide the development of ecological governance systems and briefly describe a watershed ecological governance project in south-central Texas. Ecological governance is a form of governance embedding ecological principles and values in all levels of decision making and action, from the personal to the global. The model of ecological governance discussed here incorporates ideas and approaches that are already being put into practice in many watershed governance projects in the US and abroad; it is based on the premise that contemporary governance systems will continue to evolve in this direction, incorporating more and more of the features of ecological governance. The watershed governance project described here was devised to ensure that the long-term ecological integrity of a small urbanazing waterhed in south-central Texas is preserved and that the water quality standards are maintained for present and future generations. The ecological integrity of small spring-fed watersheds in Texas are under serious threat due to rapid urban development dependent on groundwater supplies, continued drilling of personal wells that are exempt from pumping regulation, and lack of adequate legal jurisdiction for managing development in rural and semi-rural areas. The watershed governance project was motivated by a firm belief of local stakeholders that watershed protection is an individual as well as a community responsibility, and the recognition that a balance between growth and protection is essential to maintain watershed integrity. It is concluded that whereas emergent systems of ecological governance struggle to succeed in an institutional context oriented towards the pursuit of self-interest and competition, their acceptance will happen more readily as ecological principles and values diffuses throughout modern society.

  18. Petrogenesis of the Fifes Peak volcanics, south-central Cascades Range, Washington

    SciTech Connect

    Babcock, R.S.; Thompson, J.M.S. . Geology Dept.)

    1993-04-01

    During the late Oligocene (ca. 27--23 Ma.), a voluminous section of subduction-related basalt to rhyolite flows and interbedded pyroclastics, comprising the Fifes Peak Formation, were extruded in the south-central Cascades Range of Washington State. Microprobe analyses reveal that basalts and basaltic andesites contain megacrysts of aluminous clinopyroxene and spinel (hercynite) that may be xenocrysts derived from an upper mantle source zone or early, high pressure magmatic phases. Mass balance calculations indicate that the compositional variation of the Fifes Peak basalt and andesite was controlled mainly by high-pressure clinopyroxene-dominated fractionation, coupled with lower pressure fractionation of plagioclase + orthopyroxene + magnetite/ilmenite. Trace element data and mass balances also show that the more silicic lavas must contain a significant crustal component (such as a high Ba/Nb pelagic sediment). The dacites and rhyolites were probably formed mainly by crustal melting, rather than contamination of mantle-derived magmas. The Fifes Peak volcanics have a typical arc-type trace-element distribution with distinct depletions in Ta, Nb, and Ti and enrichment in Th and large-ion-lithophile elements. All of the analyzed Fifes Peak flows are light-rare-earth-element enrichment, with a mean La/Yb ratio of 7.6. There is no indication of an OIB mantle source array, nor the low fluid-flux subduction conditions that characterize magmas generated in the southwest Cascades. Apparently the anomalous nature of the subduction zone in that region of the Cascades arc does not extend northward to the south-central Cascades.

  19. Predicting global change effects on forest biomass and composition in south-central Siberia.

    PubMed

    Gustafson, Eric J; Shvidenko, Anatoly Z; Sturtevant, Brian R; Scheller, Robert M

    2010-04-01

    Multiple global changes such as timber harvesting in areas not previously disturbed by cutting and climate change will undoubtedly affect the composition and spatial distribution of boreal forests, which will, in turn, affect the ability of these forests to retain carbon and maintain biodiversity. To predict future states of the boreal forest reliably, it is necessary to understand the complex interactions among forest regenerative processes (succession), natural disturbances (e.g., fire, wind, and insects), and anthropogenic disturbances (e.g., timber harvest). We used a landscape succession and disturbance model (LANDIS-II) to study the relative effects of climate change, timber harvesting, and insect outbreaks on forest composition, biomass (carbon), and landscape pattern in south-central Siberia. We found that most response variables were more strongly influenced by timber harvest and insect outbreaks than by the direct effects of climate change. Direct climate effects generally increased tree productivity and modified probability of establishment, but indirect effects on the fire regime generally counteracted the direct effects of climate on forest composition. Harvest and insects significantly changed forest composition, reduced living aboveground biomass, and increased forest fragmentation. We concluded that: (1) Global change is likely to significantly change forest composition of south-central Siberian landscapes, with some changes taking ecosystems outside the historic range of variability. (2) The direct effects of climate change in the study area are not as significant as the exploitation of virgin forest by timber harvest and the potential increased outbreaks of the Siberian silk moth. (3) Novel disturbance by timber harvest and insect outbreaks may greatly reduce the aboveground living biomass of Siberian forests and may significantly alter ecosystem dynamics and wildlife populations by increasing forest fragmentation. PMID:20437957

  20. Paleotectonic implications of arkose beds in Park Shale (Middle Cambrian), Bridger Range, south-central Montana

    SciTech Connect

    Fryxell, J.C.; Smith, D.L.

    1983-08-01

    The Cambrian System in the Bridger Range of south-central Montana is part of a 450 to 500-m (1475 to 1640-ft) thick transgressive-regressive sequence of fine-grained clastic and carbonate rocks. In south-central Montana, the Park Shale is 50 m (165 ft) of green, micaceous shale with interbedded siltstone at the base and intercalated limestone at the top. However, in the northern Bridger Range, the lower 30 m (100 ft) is a prominent interval of interbedded arkosic sandstone and micaceous shale. These arkosic sandstone beds are localized in the northern Bridger Range and are unknown in the southern Bridgers and in Cambrian outcrops of surrounding areas. The occurrence of Park sandstone beds that contain orthoclase and plagioclase grains and pebbles of quartzofeldspathic gneiss requires 1) the presence of a localized island of Precambrian crystalline rock, an erosional remnant that must have risen at least 200 m (650 ft) above the surrounding Cambrian/Precambrian erosion surface and was exposed above the depositional interface through most of the Middle Cambrian, or 2) an island of Precambrian crystalline rock that was exposed by late Middle Cambrian reactivation of zones of Precambrian structural weakness. The most spatially and lithologically feasible tectonic feature along which late Middle Cambrian movement might have produced an island or series of islands is the Willow Creek-Jefferson Canyon fault zone, along which significant movement occurred during deposition of the LaHood Formation (Precambrian Y); the fault zone structurally divides the northern and southern parts of the Bridger Range, and later Paleozoic movement has been documented along this zone.

  1. Characterization and geochemistry of Devonian oil shale North Alabama - South Central Tennessee

    USGS Publications Warehouse

    Rheams, K.F.; Neathery, T.L.

    1984-01-01

    Based on the physical and chemical data obtained to date, the Devonian oil shale rock of north Alabama and south-central Tennessee appears to offer an attractive potential for future resource development. The shale rock appears to have formed in a restrictive marine environment which provided opportunity for the accumulation of marine organic matter to form sufficient kerogen. The shale contains approximately 18% to 22% organic matter which is primarily kerogen. The kerogen has a relatively high H:C ratio indicative of an alginite and/or exinite source (Type 1 and Type II kerogen) and a high proportion of alkane and saturated ring hydrocarbons. However, a few samples have low H:C ratio values and are interpreted to have been formed in a shallow water oxidizing environment. Also, there is a possibility that these low H:C values may represent mixtures of terrestrial and marine organic material suggesting lateral facies changes of the rock from marine to near shore depositional environments. Trace metal values for both the whole rock and the shale oil fraction indicate a generally high V:Ni ratio, also indicative of a marine environment. Other trace metal values are in good agreement with data from other Devonian shales. Throughout the north Alabama and south-central Tennessee study area, the average oil yield from the shale is 13.9 gallon per ton. The highest oil yield values were obtained from the middle and upper parts of the shale sequence. Based on the crude oil composition diagram (11), the Alabama-Tennessee shale oil is classified as a aromatic-intermediate oil Estimated reserves of inplace shale oil resources in the principal study area, under less than 200 feet of overburden, exceeds 12.5 billion barrels.

  2. Late Quaternary Tephrostratigraphy of South-Central Chile (~ 38 - 40 °S)

    NASA Astrophysics Data System (ADS)

    Fontijn, K.; Rawson, H. L.; Van Daele, M. E.; Moernaut, J.; Abarzúa, A. M.; Pyle, D. M.; Mather, T. A.; De Batist, M. A. O.; Moreno-Roa, H.; Naranjo, J. A.

    2014-12-01

    The volcanoes of the Siete Lagos region ("Lake District") in South-Central Chile form part of the Southern Volcanic Zone of the Andes and include some of the most active volcanoes in South America, i.e. Villarrica and Llaima. The Late Quaternary (~ last 15 ka) regional tephrostratigraphic record for this region is however still poorly developed. We combine detailed stratigraphic logging of terrestrial sections in the vicinity of Llaima, Sollipulli, Villarrica, Quetrupillan, Mocho-Choshuenco and Puyehue-Cordón Caulle volcanoes with petrological, whole-rock and glass geochemical data, and 14C dating on charcoal entrained in volcanic deposits, and correlate the on-land sequences with tephra layers in existing 14C-dated lacustrine records of Laguna Las Ranas and Lagos Villarrica, Calafquén and Riñihue. The combined record includes previously described major eruptions, e.g. Llaima Pumice (Llaima) and Alpehue Pumice (Sollipulli), which help to constrain the relative timing of events. These correlations suggest that several widespread volcanic units are several hundreds to thousands of years older than previously thought. The record also includes newly described pumice-producing events, e.g. for the poorly studied Quetrupillan volcano, and provides new insights into the post-glacial eruptive frequency in the Southern Volcanic Zone. The newly updated stratigraphy with high-quality geochemical data also contributes to the regional tephrochronological framework which helps to significantly improve age models for lacustrine palaeoseismological and palaeoenvironmental archives.

  3. Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies

    NASA Astrophysics Data System (ADS)

    Bianchi, Clara Eugenia; Mendoza, Luciano Pedro Oscar; Fernández, Laura Isabel; Natali, María Paula; Meza, Amalia Margarita; Francisco Moirano, Juan

    2016-07-01

    Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.

  4. Applications of SEASAT altimeter data in seismotectonic studies of the South-Central Pacific

    SciTech Connect

    Sailor, R.V.; Okal, E.A.

    1983-02-28

    Individual tracks of SEASAT altimeter data can be used effectively to identify significant bathymetric features in remote and unsurveyed ocean areas. It is especially important, for studies of oceanic seismicity, to identify correlation (or lack of correlation) between seismicity and bathymetric features. However, in many seismically active regions, bathymetric data are sparse or nonexistent. A typical example is the south-central Pacific, an area studied by Okal et al. (1980), who identified several sites of active intraplate seismicity. The purpose of the present paper is to demonstrate how SEASAT data can be used to aid in bathymetric and seismotectonic interpretation of this remote ocean area. We present two illustrations: (1) SEASAT observations of Macdonald seamount, a volcanically active seamount representing the youngest member in the Austral Island chain, and (2) SEASAT observation of a previously undiscovered fracture zone located at approximately 21.4 /sup 0/S and trending east-west between 232 /sup 0/E and 236 /sup 0/E. This fracture zone is located approximately 70 km to the south of a small region of active seismicity (96 events of magnitude greater than 2.7 from 1976 to 1980). On the basis of the demonstrated ability to observe active seamounts such as Macdonald and small fracture zones, we conclude that the observed seismicity in the region near 21 /sup 0/S, 233 /sup 0/E is due to intraplate stresses but is not associated with large-scale volcanism or with an active or fossil fracture zone.

  5. Digital Data from the Great Sand Dunes and Poncha Springs Aeromagnetic Surveys, South-Central Colorado

    USGS Publications Warehouse

    Drenth, B.J.; Grauch, V.J.S.; Bankey, Viki; New Sense Geophysics, Ltd.

    2009-01-01

    This report contains digital data, image files, and text files describing data formats and survey procedures for two high-resolution aeromagnetic surveys in south-central Colorado: one in the eastern San Luis Valley, Alamosa and Saguache Counties, and the other in the southern Upper Arkansas Valley, Chaffee County. In the San Luis Valley, the Great Sand Dunes survey covers a large part of Great Sand Dunes National Park and Preserve and extends south along the mountain front to the foot of Mount Blanca. In the Upper Arkansas Valley, the Poncha Springs survey covers the town of Poncha Springs and vicinity. The digital files include grids, images, and flight-line data. Several derivative products from these data are also presented as grids and images, including two grids of reduced-to-pole aeromagnetic data and data continued to a reference surface. Images are presented in various formats and are intended to be used as input to geographic information systems, standard graphics software, or map plotting packages.

  6. Geology and geophysics of south-central Zavala and adjoining parts of Dimmit Counties, Texas

    SciTech Connect

    Noel, J.A.

    1984-09-01

    Gravity, magnetic, and seismic surveys combined with subsurface geologic investigations resulted in very intriguing interpretations of an area east of Crystal City, Texas. The study area includes the south-central part of Zavala County east of the Nueces River and the adjoining parts of Dimmit County to the south. The Elaine field is included in the study area. Gravity and magnetic residuals were calculated using the least-squares method, and the magnetic surveys revealed several serpentine plugs, which are confirmed by seismic interpretations. Although no geophysics work was done, subsurface study shows that Elaine field is the largest of these plugs. Seismic studies also show that the Austin Chalk, on whose surface the lava was extruded, is highly fractured and faulted. The Austin under the Elaine field is the lowest structural feature in the area. The Anacacho was deposited on the lava surface, and in the Elaine area it has a reeflike appearance. Isopachs of younger sediments show that they are draped and differentially compacted over the plugs, and that the Elaine plug affects sediments as young as Escondido. Production in the area is mainly from the San Miguel, but significant amounts of hydrocarbons have also been produced from Eagle Ford, Austin, Anacacho, and Olmos reservoirs.

  7. Evaluating potential effects of an industrial road on winter habitat of caribou in North-Central Alaska

    USGS Publications Warehouse

    Wilson, Ryan R.; Gustine, David D.; Joly, Kyle

    2014-01-01

    Worldwide, some caribou (Rangifer tarandus) populations are experiencing declines due partially to the expansion of industrial development. Caribou can exhibit behavioral avoidance of development, leading to indirect habitat loss, even if the actual footprint is small. Thus, it is important to understand before construction begins how much habitat might be affected by proposed development. In northern Alaska, an industrial road that has been proposed to facilitate mining transects a portion of the Western Arctic caribou herd's winter range. To understand how winter habitat use might be affected by the road, we estimated resource selection patterns during winter for caribou in a study area surrounding the proposed road. We assessed the reductions of habitat value associated with three proposed routes at three distance thresholds for disturbance. High-value winter habitat tended to occur in locally rugged areas that have not burned recently and have a high density of lichen and early dates of spring snowmelt. We found that 1.5% to 8.5% (146-848 km2) of existing high-value winter habitat in our study area might be reduced in quality. The three alternative routes were only marginally different. Our results suggest that the road would have minimal direct effects on high-value winter habitat; however, additional cumulative impacts to caribou (e.g., increased access by recreationists and hunters) should be considered before the full effects of the road can be estimated.

  8. Old Crow tephra: A new late Pleistocene stratigraphic marker across north-central Alaska and western Yukon Territory

    USGS Publications Warehouse

    Westgate, J.A.; Hamilton, T.D.; Gorton, M.P.

    1983-01-01

    Old Crow tephra is the first extensive Pleistocene tephra unit to be documented in the northwestern part of North America. It has a calc-alkaline dacitic composition with abundant pyroxene, plagioclase, and FeTi oxides, and minor hornblende, biotite, apatite, and zircon. Thin, clear, bubble-wall fragments are the dominant type of glass shard. This tephra can be recognized by its glass and phenocryst compositions, as determined by X-ray fluorescence, microprobe, and instrumental neutron activation techniques. It has an age between the limits of 60,000 and 120,000 yr, set by 14C and fission-track measurements, respectively. Old Crow tephra has been recognized in the Koyukuk Basin and Fairbanks region of Alaska, and in the Old Crow Lowlands of the northern Yukon Territory, some 600 km to the east-northeast. The source vent is unknown, but these occurrences, considered in relation to the distant locations of potential Quaternary volcanic sources, demonstrate the widespread distribution of this tephra and underscore its importance as a regional stratigraphic marker. ?? 1983.

  9. Metamorphic facies map of Alaska

    SciTech Connect

    Dusel-Bacon, C.; O-Rourke, E.F.; Reading, K.E.; Fitch, M.R.; Klute, M.A.

    1985-04-01

    A metamorphic-facies of Alaska has been compiled, following the facies-determination scheme of the Working Group for the Cartography of the Metamorphic Belts of the World. Regionally metamorphosed rocks are divided into facies series where P/T gradients are known and into facies groups where only T is known. Metamorphic rock units also are defined by known or bracketed age(s) of metamorphism. Five regional maps have been prepared at a scale of 1:1,000,000; these maps will provide the basis for a final colored version of the map at a scale of 1:2,500,000. The maps are being prepared by the US Geological Survey in cooperation with the Alaska Division of Geological and Geophysical Surveys. Precambrian metamorphism has been documented on the Seward Peninsula, in the Baird Mountains and the northeastern Kuskokwim Mountains, and in southwestern Alaska. Pre-Ordovician metamorphism affected the rocks in central Alaska and on southern Prince of Wales Island. Mid-Paleozoic metamorphism probably affected the rocks in east-central Alaska. Most of the metamorphic belts in Alaska developed during Mesozoic or early Tertiary time in conjuction with accretion of many terranes. Examples are Jurassic metamorphism in east-central Alaska, Early Cretaceous metamorphism in the southern Brooks Range and along the rim of the Yukon-Kovyukuk basin, and late Cretaceous to early Tertiary metamorphism in the central Alaska Range. Regional thermal metamorphism was associated with multiple episodes of Cretaceous plutonism in southeastern Alaska and with early Tertiary plutonism in the Chugach Mountains. Where possible, metamorphism is related to tectonism. Meeting participants are encouraged to comment on the present version of the metamorphic facies map.

  10. The typical large-scale superposed folds in the central South China: Implications for Mesozoic intracontinental deformation of the South China Block

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Dong, Shuwen; Zhang, Yueqiao; Huang, Shiqi

    2015-11-01

    The South China Block has experienced polyphase intensive intracontinental deformation in the Mesozoic time. Large-scale superposed folds in central South China document the Mesozoic tectonic events within the South China Block. Here, we present new structural data related to synfolding deformation, coupling with chronological data, to reconstruct the deformation sequence and tectonic regime during crustal shortening. These data indicate that the superposed folds, dominated by a two-stage tectonic compressive regime, experienced two phases of superposed buckle folding, leading to the orthogonal superposition of NE-SW-trending folds onto WNW-ESE-trending folds between the late Middle Jurassic and the earliest Early Cretaceous. Our structural analysis, together with geochronological data for this area, suggests that the South China Block predominately underwent two phases of intracontinental deformation during the Mesozoic. The early phase of tectonism (D1) is characterized by a late Middle Triassic to earliest Early Jurassic NE-SW compression, causing the occurrence of an orogeny-perpendicular shortening accompanying with evident magmatism. This tectonic event was most likely associated with progressive clockwise collision of the South China Block toward the north in the Indosinian event. Subsequent tectonic activity (D2) between the late Middle Jurassic and the earliest Early Cretaceous contributed to a phase of NW-SE contraction that overprinted the early NE-SW shortening in the interior of the South China Block, generating a large-scale NW-convex fold belt and the typical large-scale superposed folds within the central South China Block. The later tectonism was probably driven by the NW-directed subduction of the paleo-Pacific Plate beneath the eastern part of the Asian continent.

  11. Estrogen pollution in a highly productive ecosystem off central-south Chile.

    PubMed

    Bertin, Angéline; Inostroza, Pedro A; Quiñones, Renato A

    2011-07-01

    While the presence of steroid estrogens in the environment has become a major environmental and health concern, their occurrence in coastal sediments remains poorly characterized. In this study, we measured the levels of three natural (estrone, 17β-estradiol, estriol) and one synthetic (17α-ethinylestradiol) estrogens in 54 coastal sediment samples collected from nine locations off central-southern Chile. Steroid estrogens were found in every sample. Remarkably high levels of 17α-ethinylestradiol were detected, reaching up to 48.14 ng/g dry weight. As a result, the global estrogenic loads were estimated to be high at all sites. Interestingly, they were found to correlate with the size of human populations served by sewage plants. Our study indicates that 17α-ethinylestradiol may accumulate in coastal sediments. The possible impact of this highly potent synthetic estrogen on the biota of the marine ecosystem off central-south Chile and on human health remains an open question. PMID:21530984

  12. Structural characteristics of the central Ogcheon Belt, South Korea: orogen-parallel tectonic transport model

    NASA Astrophysics Data System (ADS)

    Kihm, You Hong; Kim, Jeong Hwan

    The rocks in the central Ogcheon Belt, South Korea, underwent three deformational phases (D 1, D 2 and D 3) during the Mesozoic Era. In the study area, NW- and NE-trending geological structures such as thrusts and folds are juxtaposed. The NW- and NE-trending folds deform isoclinal folds (F 1) with axial planar slaty cleavage (S 1), and have axial planar crenulation cleavage. All of these folds are overprinted by brittle faults (D 3). It is inferred from field data that the NW- and NE-trending structures are products of a single deformational phase (D 2). A very large-scale inclined NE-vergent isoclinal fold (F 1) produced an irregular boundary of Precambrian basement and a basement promontory, which acted as a structural obstacle against subsequent deformational phases. During the E-vergent phase (D 2), deformation partitioning occurred due to the irregular block boundary, and orogen-parallel and -orthogonal structures were produced. The D 3 phase is recognized as large-scale E-W trending structures including folds and faults. Thus, the structural evolution of the central Ogcheon Belt is related to the clockwise rotation of the maximum compressive stress axis from NE-SW to N-S during the Mesozoic Era. This study shows that the shape of colliding boundary is a very important factor in controlling the structural pattern and evolution in the study area.

  13. Gravity investigations of the Chickasaw National Recreation Area, south-central Oklahoma

    USGS Publications Warehouse

    Scheirer, Daniel S.; Scheirer, Allegra Hosford

    2006-01-01

    The geological configuration of the Arbuckle Uplift in the vicinity of Chickasaw National Recreation Area in south-central Oklahoma plays a governing role in the distribution of fresh and mineral springs within the park and in the existence of artesian wells in and around the park. A confining layer of well-cemented conglomerate lies immediately below the surface of the recreation area, and groundwater migrates from an area of meteoric recharge where rocks of the Arbuckle-Simpson Aquifer crop out as close as two kilometers to the east of the park. Prominent, Pennsylvanian-aged faults are exposed in the aquifer outcrop, and two of the fault traces project beneath the conglomerate cover toward two groups of springs within the northern section of the park. We conducted gravity fieldwork and analysis to investigate the subsurface extensions of these major faults beneath Chickasaw National Recreation Area. By defining gravity signatures of the faults where they are exposed, we infer that the Sulphur and Mill Creek Faults bend to the south-west where they are buried. The South Sulphur Fault may project westward linearly if it juxtaposes rocks that have a density contrast opposite that of that fault's density configuration in the Sulphur Syncline area. The Sulphur Syncline, whose eastern extent is exposed in the outcrop area of the Arbuckle-Simpson Aquifer, does not appear to extend beneath Chickasaw National Recreation Area nor the adjacent City of Sulphur. The South Sulphur Fault dips steeply northward, and its normal sense of offset suggests that the Sulphur Syncline is part of a graben. The Mill Creek Fault dips vertically, and the Reagan Fault dips southward, consistent with its being mapped as a thrust fault. The Sulphur and Mill Creek Synclines may have formed as pull-apart basins in a left-lateral, left-stepping strike-slip environment. The character of the gravity field of Chickasaw National Recreation Area is different from the lineated gravity field in the area

  14. Accretion of southern Alaska

    USGS Publications Warehouse

    Hillhouse, J.W.

    1987-01-01

    Paleomagnetic data from southern Alaska indicate that the Wrangellia and Peninsular terranes collided with central Alaska probably by 65 Ma ago and certainly no later than 55 Ma ago. The accretion of these terranes to the mainland was followed by the arrival of the Ghost Rocks volcanic assemblage at the southern margin of Kodiak Island. Poleward movement of these terranes can be explained by rapid motion of the Kula oceanic plate, mainly from 85 to 43 Ma ago, according to recent reconstructions derived from the hot-spot reference frame. After accretion, much of southwestern Alaska underwent a counterclockwise rotation of about 50 ?? as indicated by paleomagnetic poles from volcanic rocks of Late Cretaceous and Early Tertiary age. Compression between North America and Asia during opening of the North Atlantic (68-44 Ma ago) may account for the rotation. ?? 1987.

  15. Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon village, Porcupine river, east-central Alaska

    USGS Publications Warehouse

    Fouch, T.D.; Carter, L.D.; Kunk, M.J.; Smith, C.A.S.; White, J.M.

    1994-01-01

    Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins. ?? 1994.

  16. The deep structure of south-central Taiwan illuminated by seismic tomography and earthquake hypocenter data

    NASA Astrophysics Data System (ADS)

    Camanni, Giovanni; Alvarez-Marron, Joaquina; Brown, Dennis; Ayala, Concepcion; Wu, Yih-Min; Hsieh, Hsien-Hsiang

    2016-06-01

    The Taiwan mountain belt is generally thought to develop above a through-going basal thrust confined to within the sedimentary cover of the Eurasian continental margin. Surface geology, magnetotelluric, earthquake hypocenter, and seismic tomography data suggest, however, that crustal levels below this basal thrust are also currently being involved in the deformation. Here, we combine seismic tomography and earthquake hypocenter data to investigate the deformation that is taking place at depth beneath south-central Taiwan. In this paper, we define the basement as any pre-Eocene rifting rocks, and use a P-wave velocity of 5.2 km/s as a reference for the interface between these rocks and their sedimentary cover. We found that beneath the Coastal Plain and the Western Foothills clustering of hypocenters near the basement-cover interface suggests that this interface is acting as a detachment. This detachment is located below the basal thrust proposed from surface geology for this part of the mountain belt. Inherited basement faults appear to determine the geometry of this detachment, and their inversion in the Alishan area result in the development of a basement uplift and a lateral structure in the thrust system above them. However, across the Shuilikeng and the Chaochou faults, earthquake hypocenters define steeply dipping clusters that extend to greater than 20 km depth, above which higher velocity basement rocks are uplifted beneath the Hsuehshan and Central ranges. We interpret these clusters to form a deeply penetrating, east-dipping ramp that joins westward with the detachment at the basement-cover interface. It is not possible to define a basal thrust to the east, beneath the Central Range.

  17. A seismological study of the 1835 seismic gap in south-central Chile

    NASA Astrophysics Data System (ADS)

    Campos, J.; Hatzfeld, D.; Madariaga, R.; Lopez, G.; Kausel, E.; Zollo, A.; Iannacone, G.; Fromm, R.; Barrientos, S.; Lyon-Caen, H.

    2002-09-01

    We study the possible seismic gap in the Concepción-Constitución region of south-central Chile and the nature of the M=7.8 earthquake of January 1939. From 1 March to 31 May 1996 a seismic network of 26 short period digital instruments was deployed in this area. We located 379 hypocenters with rms travel time residuals of less than 0.50 s using an approximate velocity distribution. Using the VELEST program, we improved the velocity model and located 240 high precision hypocenters with residuals less than 0.2 s. The large majority of earthquakes occurred along the Wadati-Benioff zone along the upper part of the downgoing slab under central Chile. A few shallow events were recorded near the chain of active volcanos on the Andes; these events are similar to those of Las Melozas near Santiago. A few events took place at the boundary between the coastal ranges and the central valley. Well constrained fault plane solutions could be computed for 32 of the 240 well located events. Most of the earthquakes located on the Wadati-Benioff zone had "slab-pull" fault mechanism due to tensional stresses sub-parallel to the downgoing slab. This "slab-pull" mechanism is the same as that of eight earthquakes of magnitude around 6 that are listed in the CMT catalog of Harvard University for the period 1980-1998. This is also the mechanism inferred for the large 1939 Chilean earthquake. A very small number of events in the Benioff zone had "slab-push" mechanisms, that is events whose pressure axis is aligned with the slab. These events are found in double layered Wadati-Benioff zones, such as in northern Chile or Japan. Our spatial resolution is not good enough to detect the presence of a double layer, but we suspect there may be one.

  18. Prevalence of Pulmonary Tuberculosis among Prison Inmates at Mbarara Central Prison, South Western Uganda

    PubMed Central

    Owokuhaisa, Judith; Thokerunga, Eric; Bazira, Joel

    2015-01-01

    Aims This study was conducted to determine the prevalence of tuberculosis among prison inmates at Mbarara Central prison Design A cross sectional study was carried out at Mbarara Central Prison in Mbarara district, Kiswahili cell in Mbarara municipality among female and male prison in mates between June 2012 to August 2012. A questionnaire was administered to each prison inmate who consented in writing and two sputum specimens were collected and examined by Ziehl-Neelsen technique. Results At the time of the study, the prison had 900 inmates (both males and females). A total of 648 in mates were screened and 248 inmates enrolled in the study. Of the 248 inmates, 5 inmates were new cases of TB while 29 inmates were already on TB treatment. The median age of participants was 28 years (23.5-33 IQR) and 96.4% were males with majority (22.6%) coming from Mbarara as a home district. The participants had stayed in prison for a median duration of 2 years (1-3 IQR) and 23.7% had ever been in prison before. The median number of inmates per cell was 140 (138-149 IQR) and inmates (female and male) had a body mass index of 21.4 (19.9-22.6 IQR) and 20.2 (19.2-26.7 IQR) respectively. Of the inmates evaluated, 68.8% reported cough for 2 or more weeks. Other symptoms reported were weight loss (in 40.7%) and night sweats (in 35.8%). Of the 248 inmates evaluated, 95 inmates were tested for HIV and 4.1% were HIV serology positive. Conclusion The prevalence of TB in Mbarara Central prison South Western Uganda is low but calls for continued surveillance through regular TB screening. PMID:26949722

  19. Developing a chironomid training set for western South America (South-Central Chile): potential for quantitative temperature reconstructions

    NASA Astrophysics Data System (ADS)

    Araneda, A.; Larocque-Tobler, I.; Torrejon, F.; Grosjean, M.; Jana-Pinninghoff, P.; Ortega, C.; Urrutia, R.

    2012-12-01

    Quantitative climate reconstructions of the last two millennia are a fundamental issue in order to compare the current trends in climate observed nowadays. At global scale most of the climate reconstructions have been developed for the Northern Hemisphere, while for the Southern Hemisphere quantitative reconstructions are very rare and very limited geographically. The recognition of such disparity has generated among other research initiatives the LOTRED-SA Long-Term climate Reconstruction and Dynamics of (southern) South America, a collaborative, high-resolution multi-proxy approach within the framework of the IGBP-PAGES program. In this context our work presents the results of a 50-lakes training set in Central-Southern Chile developed with the aim to generate a basis for quantitative chironomid-inferred temperature reconstructions for this part of the continent. Chironomids (Insecta: Diptera) are aquatic insects that develop a great proportion of their life cycle as larvae in aquatic ecosystems. Several studies, developed mainly in the Northern Hemisphere, have proven their usefulness in reconstructing past climate due to the larvae's relationship to temperature. The training set developed here includes lakes located between 34 and 48 S, covering a broad temperature (as latitudinal) gradient. The surface (0-1 cm) sediment of each lake was sampled and chironomids, organic matter and nutrient were analyzed. Water analyses included the measurement of 10 variables (AirT, WBT, WST, N-tot, P-tot, Fe, Na, pH among others). In order to identify the most important variables explaining the highest variance in the chironomid assemblages, ordinations analyses were performed. A preliminary DCA analysis indicated, according to the length of gradients smaller than 3 STD, that a linear model was more appropriate for further analysis. Hence a RDA analysis was applied to the environmental and species data, indicating that the most important variables to determine chironomid

  20. A Comparative Overview of the Education of Deaf Children in Central America, the Caribbean and Parts of South America.

    ERIC Educational Resources Information Center

    Delgado, Gilbert L.

    This paper describes the current state of education for deaf children in Central America and the Caribbean (with some mention of parts of South America), focusing on an historical description of events and forces impacting these regions; current educational philosophies; adult associations of deaf people; intra/intercountry networking; educational…

  1. Dancing between Two Worlds: A Portrait of the Life of a Black Male Teacher in South Central LA

    ERIC Educational Resources Information Center

    Lynn, Marvin

    2006-01-01

    This article offers a portrait of a young black male teacher in an urban school in South Central Los Angeles. In the portrait, the words of the subject are intertwined with the thoughts and reactions of the researcher as a way in which to capture his life history narrative and offer his reading of the world. The article discusses the participant's…

  2. Languages of North, Central, and South America. A Survey of Materials for the Study of the Uncommonly Taught Languages.

    ERIC Educational Resources Information Center

    Johnson, Dora E.; And Others

    This is an annotated bibliography of basic tools of access for the study of the uncommonly taught languages of North, Central, and South America. It is one of eight fascicles which constitute a revision of "A Provisional Survey of Materials for the Study of the Neglected Languages" (CAL 1969). The emphasis is on materials for the adult learner…

  3. A COMPARISON OF INTER-ANALYST DIFFERENCES IN THE CLASSIFICATION OF A LANDSAT TEM+ SCENE IN SOUTH-CENTRAL VIRGINIA

    EPA Science Inventory

    This study examined inter-analyst classification variability based on training site signature selection only for six classifications from a 10 km2 Landsat ETM+ image centered over a highly heterogeneous area in south-central Virginia. Six analysts classified the image...

  4. Central and South America: Language Arts around the World, Volume II. Cross Curricular Activities for Grades 4-6.

    ERIC Educational Resources Information Center

    Fuchs, Lucy

    Suggesting that students in the intermediate grades can explore the world around them and practice valuable skills in spelling, reading, writing, communication, and language, this book presents cross-curricular units designed to integrate language-arts activities into the study of Central and South American cultures. The units in the book reach…

  5. Immigration and the Challenge of Education: A Social Drama Analysis in South Central Los Angeles. Education, Politics and Public Life

    ERIC Educational Resources Information Center

    Jaramillo, Nathalia E.

    2012-01-01

    Part enthnograpy and part testimony, this book analyzes a school setting and community from the standpoint of a group of immigrant mothers (las madres) in South Central Los Angeles who were concerned about the education of their children and the violence in their communities. Written in both the first and third person, in Spanish and English, the…

  6. A Study of the Continuing Education Needs and Interests of Managers and Professional People in South-Central Oregon.

    ERIC Educational Resources Information Center

    Easton, Edison E.

    Questionnaires were sent rendomly to 980 individuals to determine educational needs and interests of supervisors, managers, administrators, and professional people in south-central Oregon. The object was to determine the desired subject matter, time, place, approach, and instructor, and the influence of age, education, location, size of…

  7. The Wallula fault and tectonic framework of south-central Washington, as interpreted from magnetic and gravity anomalies

    SciTech Connect

    Blakely, Richard J.; Sherrod, Brian; Weaver, Craig; Wells, Ray E.; Rohay, Alan C.

    2013-11-13

    Magnetic and gravity data, collected in south-central Washington near the Yakima Fold and Thrust Belt (YFTB) are used to model upper crustal structure, the extent of the late Columbia River Basalt flow named the Ice Harbor member, the vertical conduits (dikes) that the Ice Harbor erupted from, and whether the dikes are offset or affected by faulting on the Wallula Fault zone.

  8. UNIT, ALASKA.

    ERIC Educational Resources Information Center

    Louisiana Arts and Science Center, Baton Rouge.

    THE UNIT DESCRIBED IN THIS BOOKLET DEALS WITH THE GEOGRAPHY OF ALASKA. THE UNIT IS PRESENTED IN OUTLINE FORM. THE FIRST SECTION DEALS PRINCIPALLY WITH THE PHYSICAL GEOGRAPHY OF ALASKA. DISCUSSED ARE (1) THE SIZE, (2) THE MAJOR LAND REGIONS, (3) THE MOUNTAINS, VOLCANOES, GLACIERS, AND RIVERS, (4) THE NATURAL RESOURCES, AND (5) THE CLIMATE. THE…

  9. 78 FR 35957 - Notice of Intent To Prepare a Resource Management Plan for the Central Yukon Planning Area Alaska...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... Framework Plan. Additionally, the RMP will cover lands in the Fairbanks North Star Borough that are... and traditional lifestyles; and impacts from climate change. Preliminary planning criteria include: 1... Bureau of Land Management Notice of Intent To Prepare a Resource Management Plan for the Central...

  10. IN THE FOOTSTEPS OF ROBERT MARSHALL: PROPOSED RESEARCH OF TREE LINE MIGRATION AND GROWTH IN THE CENTRAL BROOKS RANGE, ALASKA

    EPA Science Inventory

    The proposed research will quantify white spruce growth and document its latitudinal stability at the tree limit in the central Books Range over the life span of the living trees. he goal is to link tree growth and tree position to summer temperature and precipitation. istorical ...

  11. Vitrinite reflectance data for Cretaceous marine shales and coals in the Bighorn Basin, north-central Wyoming and south-central Montana

    USGS Publications Warehouse

    Pawlewicz, Mark J.; Finn, Thomas M.

    2012-01-01

    The Bighorn Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 10,400 square miles in north-central Wyoming and south-central Montana. The purpose of this report is to present new vitrinite reflectance data collected from Cretaceous marine shales and coals in the Bighorn Basin to better characterize the thermal maturity and petroleum potential of these rocks. Ninety-eight samples from Lower Cretaceous and lowermost Upper Cretaceous strata were collected from well cuttings from wells stored at the U.S. Geological Survey (USGS) Core Research Center in Lakewood, Colorado.

  12. Evolution of the snow area index of the subarctic snowpack in central Alaska over a whole season. consequences for the air to snow transfer of pollutants.

    PubMed

    Taillandier, A S; Domine, F; Simpson, W R; Sturm, M; Douglas, T A; Severin, K

    2006-12-15

    The detailed physical characteristics of the subarctic snowpack must be known to quantify the exchange of adsorbed pollutants between the atmosphere and the snow cover. For the first time, the combined evolutions of specific surface area (SSA), snow stratigraphy, temperature, and density were monitored throughout winter in central Alaska. We define the snow area index (SAI) as the vertically integrated surface area of snow crystals, and this variable is used to quantify pollutants' adsorption. Intense metamorphism generated by strong temperature gradients formed a thick depth hoar layer with low SSA (90 cm(2) g-1) and density (200 kg m(-3)), resulting in a low SAI. After snowpack buildup in autumn, the winter SAI remained around 1000 m(2)/m(2) of ground, much lower than the SAI of the Arctic snowpack, 2500 m(2) m-(2). With the example of PCBs 28 and 180, we calculate that the subarctic snowpack is a smaller reservoir of adsorbed pollutants than the Arctic snowpack and less efficiently transfers adsorbed pollutants from the atmosphere to ecosystems. The difference is greater for the more volatile PCB 28. With climate change, snowpack structure will be modified, and the snowpack's ability to transfer adsorbed pollutants from the atmosphere to ecosystems may be reduced, especially for the more volatile pollutants. PMID:17256489

  13. Extending airborne electromagnetic surveys for regional active layer and permafrost mapping with remote sensing and ancillary data, Yukon Flats ecoregion, central Alaska

    USGS Publications Warehouse

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Minsley, Burke J.; Ji, Lei; Walvoord, Michelle A.; Smith, Bruce D.; Abraham, Jared D.; Rose, Joshua R.

    2013-01-01

    Machine-learning regression tree models were used to extrapolate airborne electromagnetic resistivity data collected along flight lines in the Yukon Flats Ecoregion, central Alaska, for regional mapping of permafrost. This method of extrapolation (r = 0.86) used subsurface resistivity, Landsat Thematic Mapper (TM) at-sensor reflectance, thermal, TM-derived spectral indices, digital elevation models and other relevant spatial data to estimate near-surface (0–2.6-m depth) resistivity at 30-m resolution. A piecewise regression model (r = 0.82) and a presence/absence decision tree classification (accuracy of 87%) were used to estimate active-layer thickness (ALT) (< 101 cm) and the probability of near-surface (up to 123-cm depth) permafrost occurrence from field data, modelled near-surface (0–2.6 m) resistivity, and other relevant remote sensing and map data. At site scale, the predicted ALTs were similar to those previously observed for different vegetation types. At the landscape scale, the predicted ALTs tended to be thinner on higher-elevation loess deposits than on low-lying alluvial and sand sheet deposits of the Yukon Flats. The ALT and permafrost maps provide a baseline for future permafrost monitoring, serve as inputs for modelling hydrological and carbon cycles at local to regional scales, and offer insight into the ALT response to fire and thaw processes.

  14. Tectonic framework of petroliferous rocks in Alaska: hydrocarbons

    USGS Publications Warehouse

    Grantz, Arthur; Kirschner, C.E.

    1976-01-01

    Alaska, which contains about 28% of the land and continental shelf of the United States, is estimated by the U.S. Geological Survey to contain about one third of the nation's undiscovered oil and about one sixth of its undiscovered natural gas. The Survey estimates that fields discovered in Alaska through 1972 ultimately may produce about 26 billion bbl of oil and 68 Tcf of natural gas. In northern Alaska, Paleozoic and Mesozoic shelf and slope carbonate and clastic rocks of the Brooks Range orogen were thrust relatively northward over the depressed south margin of the Paleozoic and Mesozoic Arctic platform. A foredeep, the Colville geosyncline, developed across the depressed margin of the platform in earliest Cretaceous time. Detritus from the Brooks Range filled the foredeep and prograded northward to fill the Cretaceous and Tertiary North Chukchi and Umiat-Camden basins and form the progradational Beaufort shelf. The largest petroleum reserves (Prudhoe Bay and associated fields) and the best prospects for additional large discoveries in Alaska lie in the areally extensive upper Paleozoic to Tertiary carbonate and clastic rocks of northern Alaska. In southern Alaska, a series of arc-trench systems developed on oceanic rocks during Jurassic and Cretaceous time. Between these arcs and the metamorphic (continental) terranes of east-central and northern Alaska, large back-arc and arc-trench gap basins received thick volcanic and detrital deposits. These deposits were extensively, and commonly intensely, deformed and disrupted by mid-Jurassic to Tertiary plutonism, Laramide oroclinal bending, wrench faulting, and arc-related compression. This deformation, coupled with low porosity (in part produced by diagenetic mobilization of labile constituents), has left these rocks with only modest, local prospects for petroleum. Laramide events compressed and consolidated ("continentalized") the late Mesozoic back-arc basin deposits and welded them to the older continental

  15. Biomarker evidence for increasing aridity in south-central India over the Holocene

    NASA Astrophysics Data System (ADS)

    Sarkar, S.; Wilkes, H.; Prasad, S.; Brauer, A.; Basavaiah, N.; Strecker, M. R.; Sachse, D.

    2012-12-01

    Summer monsoonal rainfall has played an important role in the development and sustenance of the largely agro-based economy in the Indian subcontinent in the recent past. A better understanding of past variations in monsoonal rainfall can therefore lead to an assessment of its potential impact on early human societies. However, our knowledge of spatiotemporal patterns of past monsoon strength, as inferred from proxy records, is limited due to the lack of high-resolution paleo-hydrological records from continental archives. Here, we reconstruct centennial-scale hydrological variability associated with changes in the intensity of the Indian Summer Monsoon based on a record of lipid biomarker abundances and compound-specific stable isotopic composition of a 10-m-long sediment core from saline-alkaline Lonar Lake, situated in the core 'monsoon zone' of south-central India. We identified three periods of distinct hydrology over the Holocene in south-central India. The period between 10.4 and 6.5 ka BP was characterized by a relatively high abundance of land-plant biomarkers, such as long-chain n-alkanes. The composition of these leaf-wax n-alkanes (weighted average of concentration of different chain-length n-alkanes, expressed as the ACL index) and their negative δ13C (-30‰ to -33 ‰) indicate the dominance of woody C3 vegetation in the catchment, and negative δD (-170‰ to -175‰) values argue for a wet period due to an intensified monsoon. Rapid fluctuations in abundance of both terrestrial and aquatic biomarkers between 6.5 and 4 ka BP indicate an unstable lake ecosystem, culminating in a transition to arid conditions. Higher ACL values and a pronounced shift to more positive δ13C values (up to -22‰) of leaf-wax n-alkanes over this period indicate a change of dominant vegetation to C4 grasses. Along with a 40‰ increase in leaf wax n-alkane δD values, which likely resulted from less rainfall and/or higher plant evapotranspiration, we interpret this period

  16. 3D Anisotropic structure of the south-central Mongolia from Rayleigh and Love wave tomography

    NASA Astrophysics Data System (ADS)

    Yu, D.; Wu, Q.; Montagner, J. P.

    2014-12-01

    A better understanding of the geodynamics of the crust and mantle below Baikal-Mongolia is required to identify the role of mantle processes versus that of far-field tectonic effects from India-Asia collision. Anisotropy tomography can provide new perspective to the continental growth mechanism. In order to study the 3D anisotropic structure of the upper mantle in the south-central Mongolia, we collected the vertical and transverse components of seismograms recorded at 69 broadband seismic stations. We have measured inter-station phase velocities of 7181 Rayleigh waves and 901 Love waves using the frequency-time analysis of wavelet transformation method for the fundamental mode at period range 10~80s. The lateral phase velocity variations are computed by using a regionalization method. These phase velocities have been inverted to obtain the first anisotropic model including Sv velocities, azimuthal and radial anisotropy. The Middle Gobi is associated with low velocity. Based on the distribution of the Cenozoic basalts in the Middle Gobi, it refers that the low velocity anomaly is related to the Cenozoic volcanism. In the northern domain, near to Baikal zone, the azimuthal anisotropy is normal to the Baikal rift and consistent with the fast direction of previous SKS splitting measurements. In the South Gobi, north to Main Mongolian Lineament, the azimuthal anisotropy is NEE-SWW in the crust and NW-SE in the mantle. It indicates that the crust and mantle are decoupled. We propose that the crustal deformation is related to the far-field effects of India-Asia collision and that the mantle flow is correlated with the Baikal rift activity. Further study in process will provide more evidence and insight to better understand the geodynamics in this region.

  17. Northwest coast of United States to Central South America at Night

    NASA Video Gallery

    This video was taken on August 19, 2011 from 08:56:00 to 09:22:18 GMT from the ISS. This pass begins just southeast of Alaska, and the first cities that the ISS passes over (seen approximately 10 s...

  18. 3. Northwest coast of United States to Central South America at Night

    NASA Video Gallery

    This video was taken on August 19, 2011 from 08:56:00 to 09:22:18 GMT from the ISS. This pass begins just southeast of Alaska, and the first cities that the ISS passes over (seen approximately 10 s...

  19. Foraminiferal zonation and carbonate facies of Carboniferous (Mississippian and Pennsylvanian) Lisburne group, central and eastern Brooks range, Arctic Alaska

    USGS Publications Warehouse

    Armstrong, Augustus K.; Mamet, Bernard L.; Dutro, J. Thomas

    1970-01-01

    The Lisburne Group carbonate rocks of the central and eastern Brooks Range contain foraminiferal assemblages assigned to zones of late Tournaisian (Osage) to early Moscovian (Atoka) age. Representatives of both Eurasiatic and American cratonic microfaunas permit correlation with the original Carboniferous type sections in western Europe as well as with the standard Mississippian and Pennsylvanian sequences in the Mid-Continent region of North America. Correlation anomalies in the lower part of the sequence are discussed.

  20. The Central Atlantic Magmatic Province: Age Comparison Between the South Carolina Dykes and Morocco Lava Flows

    NASA Astrophysics Data System (ADS)

    Youbi, N.; Nomade, S.; Breutel, E.; Knight, K.

    2003-12-01

    Believed to be the largest volcanic province on Earth at more than 6000 km long and 2000 km wide, the Central Atlantic Magmatic Province (CAMP) stretches from Eastern Canada to Brazil and from Western Spain to the Ivory Coast. Due to the massive erosion and subsequent in filling of these areas since the 200 Ma rifting event, dikes and sills constitute the majority of the exposed CAMP volcanics. However, well preserved lava flows have been found in the Triassic basins of the Northeastern United States and Morocco. Despite numerous 40Ar/39Ar dating attempts, very few of the exposed CAMP volcanics have been successfully dated due to a variety of factors including; excess argon and alteration. Especially no age is available in the well-mapped but structurally complex South and North Carolina dykes swarm as well as only few scattered ages in the Moroccan Trias-Liassic basins. Our goal is to better constrain the emplacement timing of the dykes swarm but also to compare age of both intrusive and effusive rocks from the same magmatic event but separated from more than 1000 km, 200 Mys ago. Several questions continue to surround the CAMP volcanic province including its cause and emplacement mechanism. Toward that end we have collected and dated dyke samples from the Carolinas and flows in Morocco, 1000 km away and across the rift. We anticipate that a comparison of these dates will enable us to understand more about the timing between the emplacement of the flows and dykes. We have collected in South Carolina and High Atlas in Morocco 7 and 9 hand samples respectively. Specimens from South Carolina correspond to the three distinct dykes' direction NE-SW, NW-SE and NS. In Morocco, samples were collected in four sections (100 to 300 m thick) located in the High Atlas between Marrakech and Ouarzazate. From each hand sample two different transparent plagioclase fractions, 250-180 and 180 to 100 microns, were separated. We have performed step heating experiments at the Berkeley

  1. How Socio-Economic Conditions Influence Forest Policy Development in Central and South-East Europe

    NASA Astrophysics Data System (ADS)

    Vuletić, Dijana; Potočić, Nenad; Krajter, Silvija; Seletković, Ivan; Fürst, Christine; Makeschin, Franz; Galić, Zoran; Lorz, Carsten; Matijašič, Dragan; Zupanič, Matjaž; Simončič, Primož; Vacik, Harald

    2010-12-01

    In this article, several findings on socio-economic conditions derived from national reports and a web-based questionnaire are discussed and related to the changing role of forestry and the future forest policy development. A number of Central and South-eastern European countries taking part in a SEE-ERA-NET project ReForMan project ( www.reforman.de ) participated in data acquisition: Austria, Bosnia and Herzegovina, Croatia, Germany, Serbia and Slovenia. The aim of the research was to illustrate the present structure of forestry sector, as well as investigate newly emerging topics in forestry of Central and South-eastern Europe. The results indicated certain patterns in attitudes and perceptions among stakeholders that can be related to socio-economic conditions defined for each country. Clear differences between member and non-member countries exist only in level of implementation of EU legislation. Results showed consensus on main threats to the forests among all countries, but also some country specifics in perceptions of factors influencing forestry, their importance and professional competencies. These results could be additionally explained by influence of historical conditions which shaped development of forest sector in SEE region especially in its organizational dimension as well as in perceived role of forestry expressed through recognition of main forest functions. The influence of European forest policy processes in the region is evident through adaptation of EU legislation and perceived implications of international processes on national levels. Based on this observation, two possible options for future development of the forestry sector can be foreseen: (i) focusing on the productive function of forests and fostering its' sustainable use; or (ii) putting an emphasis on environmental and social issues. In both cases supporting public

  2. Mobile LiDAR Measurement for Aerosol Investigation in South-Central Hebei, China

    NASA Astrophysics Data System (ADS)

    qin, kai; Wu, Lixin; Zheng, Yunhui; Wong Man, Sing; Wang, Runfeng; Hu, Mingyu; Lang, Hongmei; Wang, Luyao; Bai, Yang; Rao, Lanlan

    2016-04-01

    With the rapid industrialization and urbanization in China during the last decades, the increasing anthropogenic pollutant emissions have significantly caused serious air pollution problems which are adversely influencing public health. Hebei is one of the most air polluted provinces in China. In January 2013, an extremely severe and persistent haze episode with record-breaking PM2.5 outbreak affecting hundreds of millions of people occurred over eastern and northern China. During that haze episode, 7 of the top 10 most polluted cities in China were located in the Hebei Province according to the report of China's Ministry of Environmental Protection. To investigate and the spatial difference and to characterize the vertical distribution of aerosol in different regions of south-central Hebei, mobile measurements were carried out using a mini micro pulse LiDAR system (model: MiniMPL) in March 2014. The mobile LiDAR kit consisting of a MiniMPL, a vibration reduction mount, a power inverter, a Windows surface tablet and a GPS receiver were mounted in a car watching though the sunroof opening. For comparison, a fixed measurement using a traditional micro pulse LiDAR system (model: MPL-4B) was conducted simultaneously in Shijiazhuang, the capital of Hebei Province. The equipped car was driven from downtown Shijiazhuang by way of suburban and rural area to downtown Cangzhou, Handan, and Baoding respectively at almost stable speed around 100Km per hour along different routes which counted in total more than 1000Km. The results can be summarized as: 1) the spatial distribution of total aerosol optical depth along the measurement routes in south-central Hebei was controlled by local terrain and population in general, with high values in downtown and suburban in the plain areas, and low values in rural areas along Taihang mountain to the west and Yan mountain to the north; 2) obviously high AODs were obtained at roads crossing points, inside densely populated area and nearby

  3. Geomorphology and sedimentology of hummocky terrain, south-central Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Munro-Stasiuk, Mandy J.

    The landscape in south-central Alberta, Canada, is dominated by a suite of landforms that formed beneath the Laurentide Ice Sheet. This thesis explores the origins of those landforms, specifically hummocky terrain. Sediments in the hummocks, hummock form, and associations with other landforms are examined to determine hummock genesis. Sediment was examined from over one hundred exposures through the "Buffalo Lake Moraine" at Travers Reservoir, McGregor Reservoir, and the Little Bow River. This belt of hummocky terrain (like most hummocky terrain regions) is traditionally interpreted as forming at, or near, the stagnating margins of the Laurentide Ice Sheet by supraglacial letdown. However, hummocks in south-central Alberta contain a complex variety of sediments and materials atypical of supraglacial letdown: in situ bedrock, thrust bedrock, lodgement till, melt-out till, sorted sand and gravel, rippled sand, rhythmically-bedded sand, silt, and clay, and pervasively sheared beds. All sediment types and deformation structures were deposited, or formed, subglacially. Also, the deposits make up in situ stratigraphies that record the history of initial Laurentide Ice Sheet advance into the area (lodgment till and thrust bedrock), the extensive accumulation of water at the bed (glaciolacustrine beds), and ice stagnation (melt-out till). Regardless of the genesis of sediments in hummocks, sedimentary units and structures are abruptly truncated by the surface that represents the hummock and trough morphology, demonstrating that the hummocks are erosional forms and that they represent a landscape unconformity. Subglacial sediments predating the erosion and subglacial eskers overlying the erosion surface strongly suggest that hummock erosion was subglacial. Also, hummock morphology, lithostratigraphy correlated from hummock to hummock, abrupt truncation at the land surface, and widespread boulder lags support meltwater erosion for hummocky terrain in the region. Well

  4. Recurrent giant earthquakes in South-Central Chile revealed by lacustrine sedimentary records

    NASA Astrophysics Data System (ADS)

    Moernaut, J.; de Batist, M. A.; Heirman, K.; van Daele, M.; Brümmer, R.; Pino, M.; Urrutia, R.; Wolff, C.; Brauer, A.; Roberts, S.; Kilian, R.

    2009-12-01

    Megathrust (‘giant’) earthquakes in the South-Central Chilean subduction zone (e.g. 1960 earthquake; Mw: 9.5) cause landslides, tsunamis, soil liquefaction, coastal uplift/subsidence, volcanic eruptions, all of which pose a major threat to society. A reliable seismic hazard assessment requires establishing if such mega-events occurred in the past and determining their recurrence pattern. The Lake District (39-42°S) in South-Central Chile, located in the northern half of the 1960 earthquake rupture zone, contains several large, steep-sloped glacigenic lakes with high sedimentation rates, and whose sedimentary deposits are highly susceptible to earthquake-triggered slope instability. To establish the reoccurrence interval of earthquakes during the Late Holocene, we mapped the spatial distribution of seismically-induced sedimentary ‘event’ deposits and structures in each lake using very-high resolution seismic data, and collected a series of short gravity cores and long piston cores. Multi-proxy sedimentary analyses (color, magnetic susceptibility, density, geochemistry, grain size), radiocarbon dating, varve-counting, and tephro-stratigraphy were used to identify ‘event’ deposits in each core and correlate paleoseismic horizons across basins. The sediment sequences investigated contain four main types of earthquake-induced structures: 1) multiple mass-wasting deposits on a single stratigraphic level, which are relicts of a basin-wide, subaqueous slope instability ‘event’; 2) homogenite deposits in the deepest parts of steep basins indicative of lake seiches and tsunamis; 3) fluid-escape structures (e.g. sediment volcanoes), which reflect sudden liquefaction in buried mass-wasting deposits and subsequent vertical fluidization flow; 4) in-situ deformed units (e.g., contorted bedding) in nearly-flat layers, which reflect strong horizontal ground acceleration events. Comparison with historical earthquakes suggests the spatial extent, thickness, nature of

  5. Distribution, Character, and Importance of Sedimentary Furrows in South-Central Long Island Sound

    NASA Astrophysics Data System (ADS)

    Poppe, L.; Doran, E.; Moser, M.; Forfinski, N.; Stewart, H.; Gardner, U.; Keene, J.; Christman, E.; Ackerman, S.

    2005-05-01

    The U.S. Geological Survey, in cooperation with the Connecticut Department of Environmental Protection and the National Oceanic and Atmospheric Administration, is producing detailed geologic interpretations of the sea floor in Long Island Sound to improve our understanding of the processes that control the complex distributions of sedimentary environments and benthic habitats. Although the deeper waters of the south-central Sound are generally characterized by relatively weak bottom currents and by depositional conditions, multibeam data reveal the presence of sedimentary furrows. These erosional bedforms occur in fine-grained cohesive sediments and cover an elongate east-west trending area (~80 km2) that lies approximately 5 km off Herod Point, NY, in water depths of 31-41 m. The furrows are irregularly spaced, trend east-northeast, average 9 m wide and 0.4 m deep, and can exceed 1.9 km long. Although most of the furrows appear to taper out gradually, some furrows show a "tuning fork" joining pattern. Most of these junctions open toward the east, indicating net westward sediment transport, but a few junctions open westward suggesting that the tidal regime is important to furrow formation and that the furrows can form when water flows in either direction. The sedimentary furrows in south-central Long Island Sound, which are similar to those we have previously described along the Connecticut side of the estuary, form under recurring directionally stable tidal currents, constrained by the elongate geometry and regional bathymetry of the Sound. These conditions, in turn, produce the secondary helical and turbulent flow patterns conducive to the formation of erosional furrows. Concurrently, bioturbation by crabs not only suspends sediment, but also nutclam shells and other coarse biogenic debris, which are aligned by the secondary flow and abrade the furrows as they saltate in the oscillating tides. Through resuspension due to biological activity and the subsequent

  6. Tephrochronology of rare Plio-Pleistocene fossiferous strata in south-central Afar, Ethiopia

    NASA Astrophysics Data System (ADS)

    DiMaggio, E.; Arrowsmith, R.; Campisano, C. J.; Deino, A. L.

    2013-12-01

    Sedimentary basins in the south and central Afar Depression archive the complex structural, climatic, volcanic, and biologic development of the region during the Pliocene and Pleistocene. The lower Awash Valley in central Afar has long served as a focus for these investigations, including the extensive work conducted to place fossil assemblages (including hominins) into stratigraphic and temporal context. Here we present a detailed analysis of tephra chemistry, correlations, and ages of the newly mapped and fossiliferous area of eastern Ledi-Geraru (ELG) in the lower Awash Valley (~3-2.5 Ma). Our results allow us to construct a tephrostratigraphic framework that provides important constraints for regional studies previously lacking a calibrated sedimentary record spanning 3 to 2.7 Ma. Based on glass chemistry and morphology, 40Ar/39Ar dating of feldspars, and stratigraphic mapping, we identified 23 distinct tephras (8 of which were dated) in >100 m of newly mapped fluvial and lacustrine sediments at ELG. The oldest tuff at ELG (Kuhulta Tuff; 2.994 Ma) is exposed in lake sediments (diatomite) that lie 3-5 m above basalt flows dated to ca. 3 Ma. The youngest ELG tephra (ca. 2.44 Ma) outcrops as a lenticular channel tuff in sediments faulted against older strata (~2.7 Ma). Between these two tephras lies the Gurumaha Tuff (ca. 2.82 Ma) and the Daáma and Bulinan Tuffs (both ca. 2.85 Ma), which provide excellent stratigraphic ties across a distance of 7.5 km, allowing us to document a lateral facies change from lacustrine in northern ELG to more nearshore in the south. These tuffs also confirm the presence of a fossiferous sedimentary record spanning the late Pliocene sedimentary gap in lower Awash Valley stratigraphy (ca. 2.94 - 2.7 Ma). While the youngest and oldest tephras at ELG temporally overlap with dated tephras from the well-described Hadar (3.8 - 2.94 Ma) and Busidima (2.7 - 0.016 Ma) Formations, we have yet to confirm geochemical correlates to any tephra

  7. Mesozoic thermal history and timing of structural events for the Yukon-Tanana Upland, east-central Alaska: 40Ar/39Ar data from metamorphic and plutonic rocks

    USGS Publications Warehouse

    Dusel-Bacon, C.; Lanphere, M.A.; Sharp, W.D.; Layer, P.W.; Hansen, V.L.

    2002-01-01

    We present new 40Ar/39Ar ages for hornblende, muscovite, and biotite from metamorphic and plutonic rocks from the Yukon-Tanana Upland, Alaska. Integration of our data with published 40Ar/39Ar, kinematic, and metamorphic pressure (P) and temperature (T) data confirms and refines the complex interaction of metamorphism and tectonism proposed for the region. The oldest metamorphic episode(s) postdates Middle Permian magmatism and predates the intrusion of Late Triassic (215-212 Ma) granitoids into the Fortymile River assemblage (Taylor Mountain assemblage of previous papers). In the eastern Eagle quadrangle, rapid and widespread Early Jurassic cooling is indicated by ???188-186 Ma 40Ar/39Ar plateau ages for hornblende from plutons that intrude the Fortymile River assemblage, and for metamorphic minerals from the Fortymile River assemblage and the structurally underlying Nasina assemblage. We interpret these Early Jurassic ages to represent cooling resulting from northwest-directed contraction that emplaced the Fortymile River assemblage onto the Nasina assemblage to the north as well as the Lake George assemblage to the south. This cooling was the final stage of a continuum of subduction-related contraction that produced crustal thickening, intermediate- to high-P metamorphism within both the Fortymile River assemblage and the structurally underlying Lake George assemblage, and Late Triassic and Early Jurassic plutonism in the Fortymile River and Nasina assemblages. Although a few metamorphic samples from the Lake George assemblage yield Jurassic 40Ar/39Ar cooling ages, most yield Early Cretaceous 40Ar/39Ar ages: hornblende ???135-115 Ma, and muscovite and biotite ???110-108 Ma. We interpret the Early Cretaceous metamorphic cooling, in most areas, to have resulted from regional extension and exhumation of the lower plate, previously tectonically thickened during Early Jurassic and older convergence.

  8. Drought-induced sulphate release from a wetland in south-central Ontario.

    PubMed

    Eimers, M Catherine; Watmough, Shaun A; Buttle, James M; Dillon, Peter J

    2007-04-01

    Increased sulphate (SO(4)) export from wetlands following summer droughts in central Ontario, Canada has been associated with the delayed chemical recovery of downstream surface waters following decreased sulphur (S) emissions. Prolonged summer droughts result in a decrease or cessation of stream flow, declines in wetland water table level and oxidation of reduced S compounds to SO(4), which is subsequently flushed into drainage streams when stream flow resumes. Sulphate input-output budget calculations (1983-1995 and 1999-2001) at a conifer Sphagnum swamp in the Plastic Lake catchment, indicate that SO(4) is retained in most years but is exported on a net basis following particularly severe summer droughts that result in the cessation of stream flow for more than 54 days (95% CI: 41-72 days). Hindcast calculations using long-term (1916-2000) stream discharge records from a nearby station indicate that while droughts occurred frequently in south-central Ontario over the past 85 years, sufficiently dry conditions to cause net SO(4) export occurred in only 18 of the past 85 years, and indicate a cumulative positive SO(4) balance for the swamp (i.e. net SO(4) retention). Furthermore, the S pool at the Plastic Lake swamp has been estimated to be approximately 1500 kg S/ha in the upper 40 cm peat layer, which is large compared to the amount of net SO(4) export that occurs even in years with particularly dry summers (e.g. -43 kg S/ha in 1987/88). Together, these data suggest that the wetland S pool at Plastic Lake has not been depleted by previous droughts and will continue to sustain episodic drought-related SO(4) export for the foreseeable future. PMID:16957853

  9. GIS Representation of Coal-Bearing Areas in North, Central, and South America

    USGS Publications Warehouse

    Tewalt, Susan J.; Kinney, Scott A.; Merrill, Matthew D.

    2008-01-01

    Worldwide coal consumption and international coal trade are projected to increase in the next several decades (Energy Information Administration, 2007). A search of existing literature indicates that in the Western Hemisphere, coal resources are known to occur in about 30 countries. The need exists to be able to depict these areas in a digital format for use in Geographic Information System (GIS) applications at small scales (large areas) and in visual presentations. Existing surficial geology GIS layers of the appropriate geologic age have been used as an approximation to depict the extent of coal-bearing areas in North, Central, and South America, as well as Greenland (fig. 1). Global surficial geology GIS data were created by the U.S. Geological Survey (USGS) for use in world petroleum assessments (Hearn and others, 2003). These USGS publications served as the major sources for the selection and creation of polygons to represent coal-bearing areas. Additional publications and maps by various countries and agencies were also used as sources of coal locations. GIS geologic polygons were truncated where literature or hardcopy maps did not indicate the presence of coal. The depicted areas are not adequate for use in coal resource calculations, as they were not adjusted for geologic structure and do not include coal at depth. Additionally, some coal areas in Central America could not be represented by the mapped surficial geology and are shown only as points based on descriptions or depictions from scientific publications or available maps. The provided GIS files are intended to serve as a backdrop for display of coal information. Three attributes of the coal that are represented by the polygons or points include geologic age (or range of ages), published rank (or range of ranks), and information source (published sources for age, rank, or physical location, or GIS geology base).

  10. Reduced admixture of North Atlantic Deep Water to the deep central South Pacific during the last two glacial periods

    NASA Astrophysics Data System (ADS)

    Molina-Kescher, Mario; Frank, Martin; Tapia, Raúl; Ronge, Thomas A.; Nürnberg, Dirk; Tiedemann, Ralf

    2016-06-01

    The South Pacific is a sensitive location for the variability of the global oceanic thermohaline circulation given that deep waters from the Atlantic Ocean, the Southern Ocean, and the Pacific Basin are exchanged. Here we reconstruct the deep water circulation of the central South Pacific for the last two glacial cycles (from 240,000 years ago to the Holocene) based on radiogenic neodymium (Nd) and lead (Pb) isotope records complemented by benthic stable carbon data obtained from two sediment cores located on the flanks of the East Pacific Rise. The records show small but consistent glacial/interglacial changes in all three isotopic systems with interglacial average values of -5.8 and 18.757 for ɛNd and 206Pb/204Pb, respectively, whereas glacial averages are -5.3 and 18.744. Comparison of this variability of Circumpolar Deep Water (CDW) to previously published records along the pathway of the global thermohaline circulation is consistent with reduced admixture of North Atlantic Deep Water to CDW during cold stages. The absolute values and amplitudes of the benthic δ13C variations are essentially indistinguishable from other records of the Southern Hemisphere and confirm that the low central South Pacific sedimentation rates did not result in a significant reduction of the amplitude of any of the measured proxies. In addition, the combined detrital Nd and strontium (87Sr/86Sr) isotope signatures imply that Australian and New Zealand dust has remained the principal contributor of lithogenic material to the central South Pacific.

  11. The Phylogeography and Spatiotemporal Spread of South-Central Skunk Rabies Virus

    PubMed Central

    Kuzmina, Natalia A.; Lemey, Philippe; Kuzmin, Ivan V.; Mayes, Bonny C.; Ellison, James A.; Orciari, Lillian A.; Hightower, Dillon; Taylor, Steven T.; Rupprecht, Charles E.

    2013-01-01

    The south-central skunk rabies virus (SCSK) is the most broadly distributed terrestrial viral lineage in North America. Skunk rabies has not been efficiently targeted by oral vaccination campaigns and represents a natural system of pathogen invasion, yielding insights to rabies emergence. In the present study we reconstructed spatiotemporal spread of SCSK in the whole territory of its circulation using a combination of Bayesian methods. The analysis based on 241 glycoprotein gene sequences demonstrated that SCSK is much more divergent phylogenetically than was appreciated previously. According to our analyses the SCSK originated in the territory of Texas ~170 years ago, and spread geographically during the following decades. The wavefront velocity in the northward direction was significantly greater than in the eastward and westward directions. Rivers (except the Mississippi River and Rio Grande River) did not constitute significant barriers for epizootic spread, in contrast to deserts and mountains. The mean dispersal rate of skunk rabies was lower than that of the raccoon and fox rabies. Viral lineages circulate in their areas with limited evidence of geographic spread during decades. However, spatiotemporal reconstruction shows that after a long period of stability the dispersal rate and wavefront velocity of SCSK are increasing. Our results indicate that there is a need to develop control measures for SCSK, and suggest how such measure can be implemented most efficiently. Our approach can be extrapolated to other rabies reservoirs and used as a tool for investigation of epizootic patterns and planning interventions towards disease elimination. PMID:24312657

  12. Wisconsinan and Sangamonian climate interpreted from fossil ostracodes and vegetation in south-central Illinois

    SciTech Connect

    Curry, B.B. ); Forester, R.M. ); Zhu, Hong; Baker, R.G. . Dept. of Geology)

    1992-01-01

    The interpretation of paleoclimate during the late Illinoian, Sangamonian, and Wisconsinan Ages in the region of present south-central Illinois has been based on plant macrofossil, pollen, and vertebrate records. The ostracode records identify periods of flow across the basins and perhaps characteristics of groundwater discharge or recharge. Basins with the largest lake-to-catchment-area ratio were most sensitive to changes in effective moisture and hydrochemistry. The Sangamonian included three intervals during which the winters were warmer than those of historical record. These intervals are represented by sediment containing relatively abundant arboreal pollen, notably bald cypress and sweet gum, and the ostracode Heterocypris punctata, which lives in subtropical to tropical lakes and estuaries. H. punctata occurs with other ostracodes that require low salinity; their association indicates that precipitation typically exceeded evaporation and that the basin was affected by throughflow. The Sangamonian ended with two warm, wet episodes that sandwich an interval implying prairie lake conditions. Warmth-loving species are abundantly represented in upper Sangamonian sediments. Such warm, wet episodes are not known to have occurred in the Midcontinent during the Holocene. The top of the Sangamonian in all except the Pittsburgh Basin is capped by a layer of reworked sediment containing fluvial ostracodes and exotic mixtures of pollen, including both spruce and sweet gum but dominated by chenopods. The reworked layer is overlain by Wisconsinan sediment containing abundant pollen of boreal taxa and ostracodes that indicate basin throughflow.

  13. Comparison of GNSS integrated water vapor and NWM reanalysis data over Central and South America

    NASA Astrophysics Data System (ADS)

    Fernández, Laura Isabel; Natali, Maria Paula; Meza, Amalia; Mendoza, Luciano; Bianchi, Clara

    2016-07-01

    Integrated water vapor (IWV) derived from Global Navigation Satellite Systems (GNSS) and Numerical Weather Models (NWM) reanalysis data were compared in order to assess the consistency between the different datasets over the extended geographical region of Central and South America. The analysis was performed for the seven years period between 2007 and 2013. We analyzed two different NWM: the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis data (ERA Interim) and the Modern-Era Retrospective analysis for Research and Applications (MERRA) from the National Aeronautics and Space Administration (NASA). The statistical analysis of the differences was performed in 110 GNSS sites (GPS + GLONASS), although the most interesting results came from the 73 sites which have more than 5 years of data. The selected area involves different climate types, from polar to tropical, and it is characterized by large temporal variability of the integrated total humidity content. Moreover, the scarce coverage of operational radio sounding stations is noticeable in large areas of the selected region; hence the contribution of IWV-GNSS is essential to improve the weather understanding. Considering that the atmospheric water vapor has a highly variable and complex distribution which knowledge is essential for weather prediction and local meteorological studies. This study aims to provide IWV-GNSS observations able to be assimilated by operational weather centers, for both prediction and simulation, as well for improving regional modeling.

  14. Assessment of Hazards Associated with the Bluegill Landslide, South-Central Idaho

    USGS Publications Warehouse

    Ellis, William L.; Schuster, Robert L.; Schulz, William H.

    2004-01-01

    The Bluegill landslide, located in south-central Idaho, is part of a larger landslide complex that forms an area the Salmon Falls Creek drainage named Sinking Canyon Recent movement of the Bluegill landslide, apparently beginning sometime in late 1998 or early 1999, has caused a 4.5 ha area of the canyon rim to drop as much as 8 m and move horizontally several meters into the canyon. Upward movement of the toe of the landslide in the bottom of canyon has created a dam that impounds a lake approximately 2 km in length. The landslide is on public administered by the U.S. Bureau of Land Management (BLM). As part of ongoing efforts to address possible public safety concerns, the BLM requested that the U.S. Geological Survey (USGS) conduct a preliminary hazard assessment of the landslide, examine possible mitigation options, and identify alternatives for further study and monitoring of the landslide. This report presents the findings of that assessment based on a field reconnaissance of the landslide on September 24, 2003, a review of data and information provided by BLM and researchers from Idaho State University, and information collected from other sources.

  15. Greenhouse gas fluxes of a shallow lake in south-central North Dakota, USA

    USGS Publications Warehouse

    Tangen, Brian; Finocchiaro, Raymond; Gleason, Robert A.; Dahl, Charles F.

    2016-01-01

    Greenhouse gas (GHG) fluxes of aquatic ecosystems in the northern Great Plains of the U.S. represent a significant data gap. Consequently, a 3-year study was conducted in south-central North Dakota, USA, to provide an initial estimate of GHG fluxes from a large, shallow lake. Mean GHG fluxes were 0.02 g carbon dioxide (CO2) m−2 h−1, 0.0009 g methane (CH4) m−2 h−1, and 0.0005 mg nitrous oxide (N2O) m−2 h−1. Fluxes of CO2 and CH4 displayed temporal and spatial variability which is characteristic of aquatic ecosystems, while fluxes of N2O were consistently low throughout the study. Comparisons between results of this study and published values suggest that mean daily fluxes of CO2, CH4, and N2O fromLong Lakewere low, particularly when compared to the well-studied prairie pothole wetlands of the region. Similarly, cumulative seasonal CH4 fluxes, which ranged from 2.68–7.58 g CH4 m−2, were relatively low compared to other wetland systems of North America. The observed variability among aquatic ecosystems underscores the need for further research.

  16. Aeromagnetic maps with geologic interpretations for the Tularosa Valley, south-central New Mexico

    USGS Publications Warehouse

    Bath, G.D.

    1977-01-01

    An aeromagnetic survey of the Tularosa Valley in south-central New Mexico has provided information on the igneous rocks that are buried beneath alluvium and colluvium. The data, compiled as residual magnetic anomalies, are shown on twelve maps at a scale of 1:62,500. Measurements of magnetic properties of samples collected in the valley and adjacent highlands give a basis for identifying the anomaly-producing rocks. Precambrian rocks of the crystalline basement have weakly induced magnetizations and produce anomalies having low magnetic intensities and low magnetic gradients. Late Cretaceous and Cenozoic intrusive rocks have moderately to strongly induced magnetizations. Precambrian rocks produce prominent magnetic anomalies having higher amplitudes and higher gradients. The Quaternary basalt has a strong remanent magnetization of normal polarity and produces narrow anomalies having high-magnetic gradients. Interpretations include an increase in elevation to the top of buried Precambrian rock in the northern part of the valley, a large Late Cretaceous and Cenozoic intrusive near Alamogordo, and a southern extension of the intrusive rock exposed in the Jarilla Mountains. Evidence for the southern extension comes from a quantitative analysis of the magnetic anomalies..

  17. The formation of basal-type uranium deposits in south central British Columbia

    SciTech Connect

    Boyle, D.R.

    1982-08-01

    The basal-type uranium deposits in south central British Columbia occur within unconsolidated, late Miocene fluvial paleochannel sediments that overlie major fault zones within the Okanagan Highlands Intrusive Complex. Five uranium deposits have been outlined to date, of which the Blizzard (4,020 metric tons U) and Tyee (650 metric tons U) are the largest. The basement intrusive complex underlying the deposits varies in age from early Cretaceous to Eocene and is comprised of quartz monzonite, granodiorite, Coryell monzonite, porphyritic granite, and pegmatite. Uranium mineralization is present in the form of uranous (ningyoite) or uranyl (saleeite, autunite) phosphates coating clastic grains and filling voids. Because of very strong reducing conditions related to large concentrations of marcasite and organic material, ningyoite is the only uranium mineral in the Tyee deposit, whereas the Blizzard deposit contains a more complex assemblage of minerals (saleeite, autunite, ningyoite). The observed paragenetic sequence of mineral precipitation in the Blizzard deposit (autunite-saleeite-ningyoite) indicates that the uranyl minerals, saleeite and autunite, are primary. Investigations of the source of the ore-forming elements (U, Ca, Mg, PO/sub 4/) showed the deposits to be formed by the infiltration into fluvial sediments of deep-seated, structurally controlled, ground waters that migrated in a well-developed regional hydrologic system within the Complex. Research indicates that the ore-forming ground waters were cold, slightly bicarbonated (150-400 ppm), highly uraniferous (10-50 ppb), and slightly oxidizing (dissolved oxygen = 2-4 ppm).

  18. Ground beetles (Coleoptera, Carabidae) of the Hanford Nuclear Site in south-central Washington State

    PubMed Central

    Looney, Chris; Zack, Richard S.; LaBonte, James R.

    2014-01-01

    Abstract In this paper we report on ground beetles (Coleoptera: Carabidae) collected from the Hanford Nuclear Reservation and Hanford National Monument (together the Hanford Site), which is located in south-central Washington State. The Site is a relatively undisturbed relict of the shrub-steppe habitat present throughout much of the western Columbia Basin before the westward expansion of the United States. Species, localities, months of capture, and capture method are reported for field work conducted between 1994 and 2002. Most species were collected using pitfall traps, although other capture methods were employed. Trapping results indicate the Hanford Site supports a diverse ground beetle community, with over 90% of the 92 species captured native to North America. Four species collected during the study period are newly recorded for Washington State: Bembidion diligens Casey, Calosoma obsoletum Say, Pseudaptinus rufulus (LeConte), and Stenolophus lineola (Fabricius). Based on these data, the Site maintains a diverse ground beetle fauna and, due to its size and diversity of habitats, is an important repository of shrub-steppe biodiversity. PMID:24715791

  19. Oil and gas developments in South America, Central America, Caribbean area, and Mexico in 1987

    SciTech Connect

    Wiman, W.D.

    1988-10-01

    Exploration activity in South America, Central America, the Caribbean area, and Mexico in 1987 showed significant increases in seismic acquisition in Belize, Bolivia, Brazil, Costa Rica, Guatemala, Mexico, Paraguay, and Peru, and a decrease in Chile and Venezuela. Exploratory drilling increased in most major producing countries but was accompanied by a decline in development drilling. Most of the increase could be attributed to private companies fulfilling obligations under risk contracts; however, state oil companies in Bolivia, Chile, and Colombia showed significant increased activity, with only Mexico showing a decrease. Colombia again had a dramatic increase in production (29% from 1986). Noteworthy discoveries were made in Bolivia (Villamontes-1); Brazil, in the Solimoes basin (1-RUC-1-AM); Chile (Rio Honda-1); Colombia, in the Llanos basin (Austral-1, La Reforma-1, Libertad Norte-1, Cravo Este-1, and Cano Yarumal-1), in the Upper Magdalena basin (Toldado-1 and Los Mangos-1); Ecuador (Frontera-1, a joint-exploration venture with Colombia); Mexico, in the Chiapas-Tabasco region (Guacho-1 and Iridi-1), in the Frontera Norte area (Huatempo-1); Peru, in the Madre de Dios basin (Armihuari-4X); Trinidad (West East Queen's Beach-1); and Venezuela (Musipan-1X). Brazil's upper Amazon (Solimoes basin) discovery, Colombia's Upper Magdalena basin discoveries Toldado-1 and Los Mangos-1, Mexico's Chiapas-Tabasco discoveries, Peru's confirmation of the giant Cashiriari discovery of 1986, and Venezuela's success in Monagas state were the highlights of 1987. 5 figs., 8 tabs.

  20. Regional and Seasonal Diet of the Western Burrowing Owl in South-Central Nevada

    SciTech Connect

    Derek B. Hall, Paul D. Greger, Jeffrey R. Rosier

    2009-04-01

    We examined diets of Western Burrowing Owls (Athene cunicularia hypugaea) based on contents of pellets and large prey remains collected year-round at burrows in each of the 3 regions in south central Nevada (Mojave Desert, Great Basin Desert, and Transition region). The most common prey items, based on percent frequency of occurrence, were crickets and grasshoppers, beetles, rodents, sun spiders, and scorpions. The most common vertebrate prey was kangaroo rats (Dipodomys spp.). True bugs (Hemiptera), scorpions, and western harvest mice (Reithrodontomys megalotis) occurred most frequently in pellets from the Great Basin Desert region. Kangaroo rats (Dipodomys spp.) and pocket mice (Perognathinae) were the most important vertebrate prey items in the Transition and Mojave Desert regions, respectively. Frequency of occurrence of any invertebrate prey was high (>80%) in samples year-round but dropped in winter samples, with scorpions and sun spiders exhibiting the steepest declines. Frequency of occurrence of any vertebrate prey peaked in spring samples, was intermediate for winter and summer samples, and was lowest in fall samples. With the possible exception of selecting for western harvest mice in the Great Basin Desert region, Western Burrowing Owls in our study appeared to be opportunistic foragers with a generalist feeding strategy.

  1. Adapting natural resource management to climate change: The South Central Oregon and Northern Rockies Adaptation Partnerships

    NASA Astrophysics Data System (ADS)

    Halofsky, J.; Peterson, D. L.

    2015-12-01

    Concrete ways to adapt to climate change are needed to help natural resource managers take the first steps to incorporate climate change into management and take advantage of opportunities to balance the negative effects of climate change. We recently initiated two science-management climate change adaptation partnerships, one with three national forests and one national park in south central Oregon, and the other with 16 national forests, three national parks and other stakeholders in the northern Rockies region. Goals of both partnerships were to: (1) synthesize published information and data to assess the exposure, sensitivity, and adaptive capacity of key resource areas, including water use, infrastructure, fisheries, and vegetation and disturbance; (2) develop science-based adaptation strategies and tactics that will help to mitigate the negative effects of climate change and assist the transition of biological systems and management to a warmer climate; (3) ensure adaptation strategies and tactics are incorporated into relevant planning documents; and (4) foster an enduring partnership to facilitate ongoing dialogue and activities related to climate change in the partnerships regions. After an initial vulnerability assessment by agency and university scientists and local resource specialists, adaptation strategies and tactics were developed in a series of scientist-manager workshops. The final vulnerability assessments and adaptation actions are incorporated in technical reports. The partnerships produced concrete adaptation options for national forest and other natural resource managers and illustrated the utility of place-based vulnerability assessments and scientist-manager workshops in adapting to climate change.

  2. Modeling saltwater upconing in a freshwater aquifer in south-central Kansas

    USGS Publications Warehouse

    Ma, T.-S.; Sophocleous, M.; Yu, Y.-S.; Buddemeier, R.W.

    1997-01-01

    The Great Bend Prairie freshwater alluvial aquifer in south-central Kansas overlies a bedrock brine aquifer of Permian age. The continuous extraction of freshwater mainly for irrigation in this area has accelerated the upward movement of the saltwater, resulting in the deterioration of water quality. Predicting saltwater upconing is critical for maintaining a long-term supply of water of good quality to the Groundwater Management District No. 5. This paper uses a numerical model to predict the effect of saltwater upconing on the salinity of pumped water. A sensitivity analysis was conducted for estimating the effects of uncertainties in model parameters on the numerical results. The most important factors affecting the salinity of discharged water are found to be the location and nature of clay layers in the aquifer, the pumping rate, the location of the well screen, and the hydraulic conductivities of the medium. The effect of uncertainties in aquifer porosity and dispersivity on salinity is appreciable but not substantial, whereas that of recharge from precipitation in the study area is relatively insignificant. In addition, a numerical model based on the field conditions observed at the Siefkes site was constructed and calibrated to reproduce and project the variation of measured water levels and discharged groundwater concentration. Finally, a number of practical management recommendations based on this study are presented.

  3. Hydrologic impact of Great Flood of 1993 in south-central Kansas

    USGS Publications Warehouse

    Sophocleous, M.; Stern, A.J.; Perkins, S.P.

    1996-01-01

    The writers analyze the hydrologic budget and quantify the ground-water recharge impact of the Great Flood of 1993 on the Great Bend Prairie aquifer of south-central Kansas. During the summer of 1993, rainfall totals exceeded normal levels by 200% in the northern portion of the study area, while air temperature and evapotranspiration were below normal levels. This extreme event provided the opportunity to revisit previously developed recharge-estimation algorithms. Average ground-water recharge for 1993 at four index sites was estimated at 178 mm using the hybrid water-fluctuation method of Sophocleous. Employing the recharge-estimation multiple-regression methodology of Sophocleous for the area, the writers estimated the 1993 recharge to be 145 mm. Both estimates are higher than the maximum annual recharge observed at the index sites during the 1985-1992 period. A January-July 1993 hydrologic balance analysis resulted in 130 mm of recharge. The recharge caused by the flood was three to more than four times the average annual recharge of the previous eight years. The regression-based recharge-estimation methodology proved to be generally reliable, even under extreme conditions.

  4. Magnetostratigraphy, paleomagnetic correlation, and deformation of Pleistocene deposits in the south central Puget Lowland, Washington

    NASA Astrophysics Data System (ADS)

    Hagstrum, Jonathan T.; Booth, Derek B.; Troost, Kathy G.; Blakely, Richard J.

    2002-04-01

    Paleomagnetic results from Pleistocene sedimentary deposits in the central Puget Lowland indicate that the region has experienced widespread deformation within the last 780 kyr. Three oriented samples were collected from unaltered fine-grained sediments mostly at sea level to determine the magnetostratigraphy at 83 sites. Of these, 47 have normal, 18 have reversed, and 18 have transitional (8 localities) polarities. Records of reversed- to normal-polarity transitions of the geomagnetic field were found in thick sections of silt near the eastern end of the Tacoma Narrows Bridge, and again at Wingehaven Park near the northern tip of Vashon Island. The transitional horizons, probably related to the Bruhnes-Matuyama reversal, apparently fall between previously dated Pleistocene sediments at the Puyallup Valley type section (all reversed-polarity) to the south and the Whidbey Island type section (all normal-polarity) to the north. The samples, in general, are of sufficient quality to record paleosecular variation (PSV) of the geomagnetic field, and a statistical technique is used to correlate horizons with significant agreement in their paleomagnetic directions. Our data are consistent with the broad structures of the Seattle uplift inferred at depth from seismic reflection, gravity, and aeromagnetic profiles, but the magnitude of vertical adjustments is greatly subdued in the Pleistocene deposits.

  5. Studying the NDVI dynamics features for vegetation monitoring method development in the south of Central Siberia

    NASA Astrophysics Data System (ADS)

    Pugacheva, Irina

    Monitoring of vegetation state can be based on studying their dynamics features. Effective methods of satellite data interpretation using spectral feature distinctions should be applied for this purpose. Studying the time series of Normalized Difference Vegetation Index (NDVI) during growth period is one of such approaches. The analysis of NDVI temporal profile shape allows to identify vegetation objects on satellite image. The NDVI curve transformation regularities during growth period are studied in the process of study carried out. Growth rate in specific phenological phases (growth of vegetative organs; maturation and fruiting) and extreme NDVI values during total growth period are detected. Growth rate is calculated as a NDVI curve slope. The NDVI dynamics of different vegetation types (agricultural crops - wheat, oats, buckwheat; abandoned fields of different age, meadow steppe, stony steppe, feather-grass steppe, flood meadow etc.), located in the south of Central Siberia (Krasnoyarsk krai, Khakasia), has been derived and analyzed. Results of this study are as the basis for developed software, which produces the automatic identification of canopy using Terra Modis satellite measurement data.

  6. Prevalence of dog intestinal nematode parasites in south central West Virginia, USA.

    PubMed

    Savilla, Tashina M; Joy, James E; May, Jeffrey D; Somerville, Charles C

    2011-05-31

    Coprological examination was used to determine prevalence of gastrointestinal helminthes in a sample of 231 dogs (117 females and 114 males) during the summer of 2009 at a veterinary clinic in south central West Virginia, USA. Clinical signs (e.g., diarrhea, vomiting, weight gain or loss) were noted in addition to a history of anthelmintic usage. A total of 79 dogs (33.6%) were infected with one or more intestinal nematodes. Most dogs (58) were parasitized with a single species, 19 were parasitized with 2 species, and 2 were parasitized by 3 species. There was no significant difference (i.e., X(2)<3.84; P>0.05) in prevalence of infection between female and male dogs for any of the identified nematode species. The chi-square test for equality of proportions was used to determine prevalence of infection in 3 age categories of dogs (females and males combined): young dogs (≤12 months of age); mature dogs (13-83 months); and old dogs >83 months. Prevalences of infection for Ancylostoma caninum and Toxocara canis were significantly (P<0.005) higher in young dogs, whereas there was no significant difference (P>0.05) in prevalence by age category for Trichuris vulpis. Dogs exhibiting clinical signs were no more likely to harbor intestinal nematodes than dogs that were asymptomatic. Additionally, dogs receiving heartworm treatment were significantly less likely to be parasitized than dogs receiving no heartworm prophylaxis. PMID:21277089

  7. Constraining rates and trends of historical wetland loss, Mississippi River Delta Plain, south-central Louisiana

    USGS Publications Warehouse

    Bernier, Julie C.; Morton, Robert A.; Barras, John A.

    2006-01-01

    The timing, magnitude, and rate of wetland loss were described for five wetland-loss hotspots in the Terrebonne Basin of the Mississippi River delta plain. Land and water areas were mapped for 34 dates between 1956 and 2004 from historical National Wetlands Inventory (NWI) datasets, aerial photographs, and Landsat Thematic Mapper (TM) satellite images. Since 1956, the emergent land area at the five study areas in south-central Louisiana has decreased by about 50%. Comparison of the water-area curve derived from the 29 TM images with water-level records from the nearby Grand Isle, Louisiana tide gauge (NOS #8761724) clearly shows that changes in land and water areas fluctuate in response to variations in regional water levels. The magnitude of water-area fluctuations decreased from the 1980s to the 1990s as former areas of wet marsh within and immediately adjacent to the wetland-loss hotspots became permanently submerged. The most rapid wetland loss occurred during the late 1960s and 1970s. Peak wetland-loss rates during this period were two to four times greater than both the pre-1970s background rates and the most recent wetland-loss rates. These results provide constraints on predicting future delta-plain wetland losses and identify Landsat TM imagery as an important source for analyzing land- and water-area changes across the entire delta plain.

  8. The phylogeography and spatiotemporal spread of south-central skunk rabies virus.

    PubMed

    Kuzmina, Natalia A; Lemey, Philippe; Kuzmin, Ivan V; Mayes, Bonny C; Ellison, James A; Orciari, Lillian A; Hightower, Dillon; Taylor, Steven T; Rupprecht, Charles E

    2013-01-01

    The south-central skunk rabies virus (SCSK) is the most broadly distributed terrestrial viral lineage in North America. Skunk rabies has not been efficiently targeted by oral vaccination campaigns and represents a natural system of pathogen invasion, yielding insights to rabies emergence. In the present study we reconstructed spatiotemporal spread of SCSK in the whole territory of its circulation using a combination of Bayesian methods. The analysis based on 241 glycoprotein gene sequences demonstrated that SCSK is much more divergent phylogenetically than was appreciated previously. According to our analyses the SCSK originated in the territory of Texas ~170 years ago, and spread geographically during the following decades. The wavefront velocity in the northward direction was significantly greater than in the eastward and westward directions. Rivers (except the Mississippi River and Rio Grande River) did not constitute significant barriers for epizootic spread, in contrast to deserts and mountains. The mean dispersal rate of skunk rabies was lower than that of the raccoon and fox rabies. Viral lineages circulate in their areas with limited evidence of geographic spread during decades. However, spatiotemporal reconstruction shows that after a long period of stability the dispersal rate and wavefront velocity of SCSK are increasing. Our results indicate that there is a need to develop control measures for SCSK, and suggest how such measure can be implemented most efficiently. Our approach can be extrapolated to other rabies reservoirs and used as a tool for investigation of epizootic patterns and planning interventions towards disease elimination. PMID:24312657

  9. Moho geometry along a north-south passive seismic transect through Central Australia

    NASA Astrophysics Data System (ADS)

    Sippl, Christian

    2016-04-01

    Receiver functions from a temporary deployment of 25 broadband stations along a north-south transect through Central Australia are used to retrieve crustal and uppermost mantle structural constraints from a combination of different methods. Using H-K stacking as well as receiver function inversion, overall thick crust with significant thickness variation along the profile (40 to ≥ 55 km) is found. Bulk crustal vp/vs values are largely in the felsic to intermediate range, with the southernmost stations on the Gawler Craton exhibiting higher values in excess of 1.8. A common conversion point (CCP) stacking profile shows three major discontinuities of the crust-mantle boundary: (1) a two-sided Moho downwarp beneath the Musgrave Province, which has previously been associated with the Neoproterozoic to early Cambrian Petermann Orogeny, (2) a Moho offset along the Redbank Shear Zone further north attributed to the Middle to Late Paleozoic Alice Springs Orogeny, and (3) another Moho offset further north, located at the boundary between the Davenport and Warramunga Provinces, which has not been imaged before. In all cases, the difference in crustal thickness between the two sides of the offset is > 8-10 km. Unlike the two southern Moho offsets, the northernmost one does not coincide with a prominent gravity anomaly. Its location and the absence of known reactivation events in the region make it likely that it belongs to a Proterozoic suture zone that marks a previously unknown block boundary within the North Australian Craton.

  10. Middle Oxfordian Lower Kimmeridgian chert nodules in the Holy Cross Mountains, south-central Poland

    NASA Astrophysics Data System (ADS)

    Migaszewski, Zdzisław M.; Gałuszka, Agnieszka; Durakiewicz, Tomasz; Starnawska, Ewa

    2006-05-01

    This report presents the results of field and laboratory (micropaleontologic, petrographic, mineralogical, chemical and isotopic) study of Middle Oxfordian-Lower Kimmeridgian chert nodules from the Holy Cross Mountains (south-central Poland). The chert host facies represent low-energy environments characteristic of changing basinal depths with subordinate influxes of coated carbonate grains derived from a prograding platform. The optical microscopic and SEM studies indicate that the chert nodules consist of cryptocrystalline quartz with subordinate microcrystalline quartz fills and LF-chalcedony sponge spicules. No opal-A and opal-CT precursors of the crypto- and microquartz have been found. These cherts formed as a result of an episodic influx of SiO 2-rich fluids and multistage processes of direct precipitation of cryptoquartz, dissolution (etching), reprecipitation (cementation), and recrystallisation of sponge spicules composed of metastable amorphous opal-A. Of the different genetic models of chert formation, the sea-floor hydrothermal activity linked to the Mid-Polish Rift and extentional tectonics in the Carpathian area seems to be a possible hypothesis.

  11. Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana

    SciTech Connect

    Wilson, K.M. ); Dodson, P. ); Fiorillo, A.R. )

    1991-03-01

    Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana, has been the subject of intensive paleontological study for many years. However, little has been published on the sedimentology of the formation in this area. The authors have completed a preliminary field study of fluvial facies, with a view towards correcting this omission. Initial results include detailed facies descriptions and maps for five quarries along a line of transect stretching some 40 km parallel to depositional dip. Facies identified are predominantly overbank splays and levees, with common point bar/alluvial channel units and occasional small, possibly estuarine sand bodies in parts of the section. Shell beds (mainly oysters) and bedded, 1 m thick coals are also significant in some sections. Preliminary attempts at paleohydrology suggest river channels in some parts of the section were about 100 m wide and 2 m deep; however, other parts of the section exhibit much larger channel widths. Channel stacking is common. Preliminary results suggest a strong correlation between the occurrence of reddish brown carbonaceous silty shales, and dinosaur bone deposits.

  12. Mapping capacity to conduct health technology assessment in Central, Eastern and South-Eastern Europe

    PubMed Central

    Olry de Labry Lima, Antonio; García Mochón, Leticia; Caro Martínez, Araceli; Martín Ruiz, Eva; Espín Balbino, Jaime

    2016-01-01

    Aim To provide insights into the capacity to conduct health technology assessment (HTA) in Central, Eastern, and South-Eastern Europe (CESEE), taking account of technical, financial, networking, and human resources. Methods An e-mail survey of 257 CESEE key informants involved in HTA was undertaken between March and April 2014. Contact e-mail addresses were identified from the internet. The survey questionnaire consisted of 3 sections: i) characteristics of the organization performing HTA, (ii) networking in HTA, and (iii) resources allocated for HTA. Results The survey was completed by 41 respondents representing a wide range of institutions from CESEE countries (response rate of 19.8%). Less than a quarter of respondents reported that their institutions had HTA-specific budgets, whereas the majority indicated that their institutions participated in HTA networks either at domestic or international levels. Although almost half of respondents indicated that their institutions offered HTA training, a shortage in skills training was suggested as the main barrier to HTA. Conclusion This is the first survey to thoroughly assess the state of HTA capacity in the CESEE region. To strengthen HTA capacity, CESEE countries should increase financial, technical, and training resources. To strengthen collaboration, the European Union and other international bodies should assist existing HTA networks in fulfilling their regional activities through leadership, advocacy to local policymakers, funding, and technical assistance. PMID:26935616

  13. Lacustrine and paludine facies: Cretaceous Baum Limestone, south-central Oklahoma

    SciTech Connect

    Balkan, E.D.; Elmore, R.D.

    1983-03-01

    The Lower Cretaceous Baum Limestone in the Arbuckle Mountains of south-central Oklahoma was deposited in lacustrine and paludine settings near the Cretaceous shoreline. The unit rests unconformably on folded Pennsylvanian rocks and is overlain by and grades into the Paluxy Formation, a sandstone deposit with numerous Ophiomorpha burrows. The lacustrine lithofacies include the following: (1) massive micrite containing charophyte fragments and ostracodes; (2) intraformational conglomerate composed of rounded micrite clasts in a micritic matrix; (3) rounded peloids and coated peloids; (4) laminated micrite; and (5) conglomerate composed of clasts derived from Paleozoic rocks within a micritic matrix. Disintegration of charophytes that grew in the littoral zone of the lake produced the massive micrite. Intraformational conglomerates and peloids represent reworking of massive micrite whereas the other conglomerates represent fluvial influx. Features found within the paludine facies include: (1) brecciated micritic limestone that probably formed as a result of shrinking and swelling due to an oscillating phreatic water table; (2) subspherical nodules of micrite (peds) separated by red shale (plasma) that represent pedogenic alteration of exposed lacustrine mud; and (3) subcylindrial columns composed of micritic limestone representing root-casts. These paludine features formed as a result of pedogenic processes in a marsh that rimmed the shallow lake where the lacustrine facies accumulated.

  14. The environment of south-central Tunisia as observed on Landsat scene 206/036

    USGS Publications Warehouse

    Grolier, M.J.; Schultejann, P.A.

    1982-01-01

    One Landsat image in south-central Tunisia was analyzed to demonstrate the application of remote-sensing technology to regional development. A preliminary analysis included I) major landscape features; 2) gypsum-encrusted soils; and 3) phosphate-bearing beds exposed in the Gafsa mining district. The products specifically used for this report include: 1) A false-color composite (FCC), which had been linearly stretched to enhance contrast, and to which a modulation transfer function correction (a high-pass filter 3 pixels by 3 pixels wide) had been applied to enhance fine topographic relief. 2) A sinusoidally stretched false-color composite, on which mappable gypsum-encrusted soils and saline soils are detectable in greater detail than on the existing soil map of Tunisia at 1:500,000 scale. 3) A sinusoidally stretched band-ratio false-color composite, from which a thematic map of most phosphate-bearing beds in the Gafsa mining district was prepared. Recommendations for future Landsat image interpretation in Tunisia are offered.

  15. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  16. [Regional differences of inputs of organic matter and chemical fertilizer in South Central China].

    PubMed

    Liu, Huan-yao; Wu, Jin-shui; Zhou, Jiao-gen; Xiao, He-ai; Zhou, Ping

    2015-09-01

    This article analyzed the inputs of organic matter and chemical fertilizer in the cropland of South Central China, i.e., Hunan, Hubei, Guangdong and Guangxi, and then calculated the budgets of nitrogen (N), phosphorus (P) and potassium (K), based on the data from field investigations and peasant household surveys in the four provinces. The results showed that total amounts of organic matter inputs in the four provinces was ranked as follow: 8993 kg · hm(-2) in Guangxi, 6390 kg · hm(-2) in Hunan, 5012 kg · hm(-2) in Hubei, 4630 kg · hm(-2) in Guangdong, and average NPK inputs in the four provinces were ranked as follow: 777.5 kg · hm(-2) in Guangxi, 501.6 kg · hm(-2) in Hunan, 486.4 kg · hm(-2) in Hubei, 340.4 kg · hm(-2) in Guangdong. The N and P input surpluses were greatest in Guangxi (67.2% and 99.0% as for N and P, respectively) , followed by Hunan (33.2% and 50.8%), Hubei (11.8% and 11.0%), and Guangdong (7.8% and 30.0%). However, K input was deficient in Hunan, Hubei, and Guangdong (6.6%, 18.7% and 12.4%), but surplus in Guangxi (19.5%). PMID:26785554

  17. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H.; Watkins, J.S.

    1996-12-31

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  18. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H. ); Watkins, J.S. )

    1996-01-01

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  19. Controls on ground-water chemistry in the Horse Heaven Hills, south-central Washington

    USGS Publications Warehouse

    Steinkampf, W.C.; Bortleson, Gilbert C.; Packard, F.A.

    1985-01-01

    Miocene basaltic aquifers are the source of domestic and municipal water, and about 20,000 acre-feet of irrigation water annually, in the Horse Heaven Hills in south-central Washington State. Groundwater chemical variations derive from the hydraulic characteristics is of the geohydrologic system, from groundwater basalt reactions, and from irrigation. Some dissolved species concentrations increase with residence time; others decrease. Recharge area groundwaters are calcium magnesium sodium bicarbonate waters with sodium-adsorption ratios (SAR's) less than 1.0. They evolve to sodium potassium bicarbonate waters with SAR 's as high as 17. Glassy and cryptocrystalline phases of the basalt are the main sources of dissolved sodium. They dissolve by silicate hydrolysis in carbon dioxide charged waters that recharge the aquifer system. Dissolved silicon, iron, and aluminum concentrations are controlled by the solubilities of amorphous secondary alteration products, which order to silica phases, oxyhydroxides, and smectite. Carbonate mineral precipitation is induced by increasing pH from the hydrolysis reaction. Sodium and potassium concentrations increase until clinoptilolite saturation is reached and precipitation begins. Deviations from the general variation patterns are due to localized geologic structures which distort the groundwater flow system, and to the irrigation use of Columbia River water. (USGS)

  20. Validity of Drought Indices as Drought Predictors in the South-Central United States

    NASA Astrophysics Data System (ADS)

    Rohli, R. V.; Bushra, N.; Lam, N.; Zou, L.; Mihunov, V.; Reams, M.; Argote, J.

    2015-12-01

    Drought is among the most insidious types of natural disasters and can have tremendous economic and human health impacts. This research analyzes the relationship between two readily-accessible drought indices - the Palmer Drought Severity Index (PDSI) and Palmer Hydrologic Drought Index (PHDI) - and the damage incurred by such droughts in terms of monetary loss, over the 1975-2010 time period on monthly basis, for five states in the south-central U.S.A. Because drought damage in the Spatial Hazards Events and Losses Database for the United States (SHELDUSTM) is reported at the county level, statistical downscaling techniques were used to estimate the county-level PDSI and PHDI. Correlation analysis using the downscaled indices suggests that although relatively few months contain drought damage reports, in general drought indices can be useful predictors of drought damage at the monthly temporal scale extended to 12 months and at the county-wide spatial scale. The varying time lags between occurrence of drought and reporting of damage, perhaps due to varying resilience to drought intensity and duration by crop types across space, irrigation methods, and adaptation measures of the community to drought varies over space and time, are thought to contribute to weakened correlations. These results present a reminder of the complexities of anticipating the effects of drought but they contribute to the effort to improve our ability to mitigate the effects of incipient drought.

  1. Modeling and mapping regional land use/land cover change in South Central Texas

    NASA Astrophysics Data System (ADS)

    Ranatunga, T.; Messen, D.

    2014-12-01

    Houston-Galveston Area Council (H-GAC) conducted a land use/land cover (LULC) change detection study to generate information about the LULC changes in a 15-county area of South Central Texas. Such information is essential in regional planning, natural resource management, monitoring and modeling of environmental characteristics. The objectives of this study are (1) Identification of regional spatial patterns of each LULC conversion, (2) Estimation of the area coverage of each LULC conversion, and (3) Estimation of the net gain and losses of each LULC classes. To achieve these objectives, ArcGIS Spatial analysis functions and data management tools were employed in python environment. Change detection was estimated from 1992 to 2011 using datasets from NLCD (National Land Cover Database) 1992, NLCD 2001 and NOAA C-CAP (National Oceanic and Atmospheric Administration, Coastal Change Analysis Program) 2011. Through visual analysis and comparisons with aerial imagery, we established that NLCD 1992 and 2001 datasets contained more classification inaccuracies than the NOAA 2011 dataset. The misclassified cells in the 1992 and 2001 NLCD datasets were corrected to be consistent with the 2011 C-CAP dataset. The NLCD 2001 dataset was first corrected using a logical evaluation with 2011 classes in each pixel. Then the NLCD 1992 dataset was corrected using the correct 2001 dataset. After correcting 1992 dataset, a cell by cell comparison was conducted with the NOAA 2011 dataset, and individual changes were recorded.

  2. Phylogeny and biogeography of Poecilia (Cyprinodontiformes: Poeciliinae) across Central and South America based on mitochondrial and nuclear DNA markers.

    PubMed

    Ho, Adeljean L F C; Pruett, Christin L; Lin, Junda

    2016-08-01

    Poeciliids are a diverse group of small Neotropical fishes, and despite considerable research attention as models in ecology and evolutionary biology, our understanding of their biogeographic and phylogenetic relationships is still limited. We investigated the phylogenetic relationships of South and Central American Poecilia, by examining 2395 base pairs of mitochondrial DNA (ATPase 8/6, COI) and nuclear DNA (S7) for 18 species across six subgenera. Fifty-eight novel sequences were acquired from newly collected specimens and 20 sequences were obtained from previously published material. Analyses of concatenated and partitioned mitochondrial DNA and nuclear DNA sets resulted in a well-supported phylogeny that resolved several monophyletic groups corresponding to previously hypothesized subgenera and species complexes. A divergence-dating analysis supported the hypothesis of the genus Poecilia dispersing into Central America in the early Pliocene (ancestors of Psychropoecilia+Allopoecilia+Mollienesia: 7.3-2.0Mya) from predominantly South America. Subsequently, one lineage (subgenus Allopoecilia: 5.1-1.3Mya) expanded deeper into South America from Lower-Central America, and one lineage expanded from Nuclear-Central America into South America (subgenus Mollienesia: 0.71-0.14Mya). The subgenus Mollienesia diverged into three monophyletic groups that can be identified by nuptial male dorsal fin morphology and inner jaw dentition. A subclade of the unicuspid short-fins (subgenus Mollienesia) was the lineage that expanded into South America during the middle Pleistocene. Species in this subclade are now distributed across northern South America, where they are partially sympatric with Allopoecilia. However the P. (A.) caucana complex was not monophyletic, with P. (A.) wandae clustering in the Mollienesia subclade that expanded into South America. It is apparent that characters (body size, scale count, pigmentation, and gonopodium morphology) used to define the P. (A

  3. Combined Active and Passive Seismology to Study Continental Collision; Central South Island of New Zealand

    NASA Astrophysics Data System (ADS)

    Stern, T.; Okaya, D.; Baldock, G.; Scherwath, M.

    2005-12-01

    Central South Island of New Zealand is a continental region that has undergone both collision and strike-slip shear in the late Tertiary. From a tectonics, or rock-mechanics, view-point there is an interest in how the crust and mantle have been both thickened and sheared. The South Island Geophysical Transect (SIGHT) and the Southern Alps Passive Seismic Experiment (SAPSE) - both jointly funded US-NZ programs - studied these processes. Some of the most important findings came about by merging data from passive and active seismology. Three specific examples will be discussed: 1. Teleseismic P-wave delays from earthquakes in the Western Pacific are used to map a ~ 0.8-1 s speed-up in the mantle right beneath the region of thickest crust and highest topography of the collision zone. Forward modeling of this velocity anomaly shows that the amplitude of the anomaly can be explained by a 100 km-thick body that has a 7% in increase in P-wave speed. From the spatial pattern of the P-wave residuals we can also show that the high-speed body is about 80-100 km wide and roughly vertically disposed beneath the crustal root. The shape and position of the high-speed body beneath the seismically determined crustal root is consistent with it being thickened, and therefore cold, mantle lithosphere that has uniformly strained into a roughly symmetric root beneath the collision zone. 2. Pn anisotropy measurements from our onshore-offshore seismic shooting program allowed us to make mutually perpendicular determinations of Pn wave speeds at three localities. P-wave anisotropies of up to 11 ± 3%, 6.5 ± 2.5% and 0 ± 3%, were measured, depending on the distance of the measurement from the surface trace of the plate boundary (the Alpine Fault). These are necessarily minimum anisotropy values because it assumes that the two axes of measurement are those of minimum and maximum wave speed. Combining these results with SKS splitting values of ~ 2 s from passive seismology allowed us to make

  4. A comparative study of Taiwan's short-term medical missions to the South Pacific and Central America

    PubMed Central

    2012-01-01

    Background Taiwan has been dispatching an increasing number of short-term medical missions (STMMs) to its allied nations to provide humanitarian health care; however, overall evaluations to help policy makers strengthen the impact of such missions are lacking. Our primary objective is to identify useful strategies by comparing STMMs to the South Pacific and Central America. Methods The data for the evaluation come from two main sources: the official reports of 46 missions to 11 countries in Central America and 25 missions to 8 countries in the South Pacific, and questionnaires completed by health professionals who had participated in the above missions. In Central America, STMMs were staffed by volunteer health professionals from multiple institutions. In the South Pacific, STMMs were staffed by volunteer health professionals from single institutions. Results In comparison to STMMs to Central America, STMMs to the South Pacific accomplished more educational training for local health providers, including providing heath-care knowledge and skills (p<0.05), and training in equipment administration (p<0.001) and drug administration (p<0.005). In addition, language constraints were more common among missions to Central America (p<0.001). There was no significant difference in the performance of clinical service between the two regions. Conclusions Health-care services provided by personnel from multiple institutions are as efficient as those from single institutions. Proficiency in the native language and provision of education for local health-care workers are essential for conducting a successful STMM. Our data provide implications for integrating evidence into the deployment of STMMs. PMID:23270459

  5. Particulate carbonate matter in snow from selected sites in the south-central Rocky Mountains

    USGS Publications Warehouse

    Clow, D.W.; Ingersoll, G.P.

    1994-01-01

    Trends in snow acidity reflect the balance between strong acid inputs and reactions with neutralizing materials. Carbonate dust can be an important contributor of buffering capacity to snow however, its concentration in snow is difficult to quantify because it dissolves rapidly in snowmelt. In snow with neutral or acidic pH, most calcite would dissolve during sample melting if snow samples were processed using standard techniques. Here a method is described for separating particulate carbonate matter from snow. Snow samples were melted in solutions close to saturation with calcite, decreasing the dissolution rate by a factor of 100-200 compared with natural melting of snow. Particulate matter larger than 0.45 ??m in diameter was then filtered from solution and analysed for carbonate content. Particulate carbonate matter concentrations are reported for 25 sites in the south-central Rocky Mountains. Results are compared with Ca2+ and H+ concentrations and regional trends are evaluated. In Colorado, mean particulate carbonate in snow was 43 ??g kg-1 at sampling sites in the southern mountains and only 4 ??g kg-1 at sites in the northern mountains. The higher calcite concentrations in the south probably are related to the proximity of sampling sites to major outcrops of limestone. Particulate carbonate at sampling sites in Utah and Wyoming ranged from 3-35 ??g kg-1. The levels of particulate calcite measured in snow samples are sufficient to neutralize an average of 0.4 ??eq H+ kg-1 snow. Strong acid anion concentrations in samples from east of Craig, Colorado, were 30-50% higher than in samples from the Colorado Front Range, but H+ concentrations were 400-600% higher east of Craig. Relatively low Ca2+ concentrations in the samples from east of Craig indicate that the difference in snow acidity was due mostly to lower concentrations of neutralizing materials.Trends in snow acidity reflect the balance between strong acid inputs and reactions with neutralizing materials

  6. GREYBULL SANDSTONE PETROLEUM POTENTIAL ON THE CROW INDIAN RESERVATION, SOUTH-CENTRAL MONTANA

    SciTech Connect

    David A. Lopez

    2000-12-14

    Evaluation of the Lower Cretaceous Greybull Sandstone on the Crow Indian Reservation for potential stratigraphic traps in the valley-fill sandstone was the focus of this project. The Crow Reservation area, located in south-central Montana, is part of the Rocky Mountain Foreland structural province, which is characterized by Laramide uplifts and intervening structural basins. The Pryor and Bighorn mountains, like other foreland uplifts, are characterized by asymmetrical folds associated with basement-involved reverse faults. The reservation area east of the mountains is on the northwestern flank of the Powder River Basin. Therefore, regional dips are eastward and southeastward; however, several prominent structural features interrupt these regional dips. The nearly 4,000 mi{sup 2} reservation is under explored but has strong potential for increased oil and gas development. Oil and gas production is well established in the Powder River Basin of Wyoming to the south as well as in the areas north and west of the reservation. However, only limited petroleum production has been established within the reservation. Geologic relations and trends indicate strong potential for oil and gas accumulations, but drilling has been insufficient for their discovery. The Greybull Sandstone, which is part of the transgressive systems tract that includes the overlying Fall River Sandstone, was deposited on a major regional unconformity. The erosional surface at the base of the Greybull Sandstone is the +100 Ma, late Aptian-Early Albian regional unconformity of Weimer (1984). This lowstand erosional surface was controlled by a basin-wide drop in sea level. In areas where incised Greybull channels are absent, the lowstand erosional unconformity is at the base of the Fall River Sandstone and equivalent formations. During the pre-Greybull lowstand, sediment bypassed this region. In the subsequent marine transgression, streams began to aggrade and deposit sand of the lower Greybull Sandstone

  7. Geochronology of the western and central Brooks Range, Alaska: Implications for the geologic evolution of the Anarraaq and Red Dog Zn-Pb-Ag deposits

    USGS Publications Warehouse

    Rombach, C.S.; Layer, P.W.

    2004-01-01

    A compilation of published geochronology of rocks and minerals from the western and central Brooks Range provides a framework for understanding the complex history of the Brooks Range and northern Alaska. A simplified timeline of events comprises (1) Devonian extension, (2) Mississippian extension and Zn-Pb-Ag mineralization, (3) a passive interval, (4) pre-Brooks Range orogeny rock-formation and thermal event, (5) inception of Brooks Range orogeny, (6) exhumation and the end of main-stage deformation, and (7) subsequent episodic deformation. This compilation is supplemented by new 40Ar/39Ar dates of white mica from the Anarraaq and Red Dog Zn-Pb-Ag (+ barite) deposits from the western Brooks Range. The deposits are hosted in black shale and carbonate rocks of the Late Mississippian-Early Pennsylvanian Kuna Formation. Quartz-pyrite-white mica grains in sedimentary rocks above the Anarraaq deposit yield an age of 195.0 ?? 2.0 Ma, and paragenetically late quartz-pyrite-white mica from the Main orebody at the Red Dog deposit has an age of 126.1 ?? 0.7 Ma. These white micas are much younger than the age of Zn-Pb-Ag mineralization at Red Dog (338 ?? 5.8 Ma Re-Os age of pyrite). The date for white mica from Anarraaq (???195 Ma) appears to be related to a large-scale thermal event in the region immediately before the inception of the Brooks Range orogeny. The white mica from the Red Dog deposit (???126 Ma) correlates with the later stages of the orogeny, a period of blueschist metamorphism, extension, and rapid exhumation, which varied with geographic location. These dates suggest that the Red Dog deposits underwent significant hydrothermal overprinting during multiple episodes of the Brooks Range orogeny. ?? 2004 by Economic Geology.

  8. Multi-decadal trends in spring arrival of avian migrants to the central Arctic coast of Alaska: Effects of environmental and ecological factors

    USGS Publications Warehouse

    Ward, David; Helmericks, J.; Hupp, Jerry; McManus, L.; Budde, Michael; Douglas, David C.; Tape, K.D.

    2015-01-01

    Warming in the Arctic has caused the transition from winter to summer to occur weeks earlier over the last half century, yet little is known about whether avian migrants have altered their timing of arrival on breeding areas to match this earlier seasonal transition. Over a 50-yr period, we examined trends in the timing of the first arrival for 16 avian migrant species at the terminus of their northward migration along the central Arctic coast of Alaska and compared these trends to factors potentially influencing migration phenology. Date of first arrival occurred an average of 0.12 d yr−1 or 6 d (range = 3–10 d) earlier across all species and did not differ significantly among species between 1964 and 2013. Local climatic variables, particularly temperature, had a greater effect on a species first arrival date than did large-scale climatic predictors. First arrival date was 1.03 d earlier for every 1°C annual change in temperature, but there was nearly a 2-fold difference in the range of responses across species (0.69–1.33 d °C−1), implying that some species did better than others at timing their arrival with changing temperature. There was weak support for an influence of foraging strategy, migration distance, and flight path on timing of first arrival. Our findings, like others from temperate latitudes, indicate that avian migrants are responsive to changing environmental conditions, though some species appear to be more adaptive than others.

  9. Preliminary results, Central Gneiss Complex of the Coast Range batholith, southeastern Alaska: the roots of a high-K, calc-alkaline arc?

    USGS Publications Warehouse

    Barker, F.; Arth, Joseph G.

    1984-01-01

    The Central Gneiss Complex (CGC) of the Coast Range batholith is the oldest unit of the batholith east of Ketchikan, Alaska, being dated by the zircon UPb method (by T.W. Stern) at 128-140 Ma. Heterogeneous, layered, commonly migmatitic, orthogneiss of hornblende-biotite quartz diorite, tonalite, quartz monzodiorite and granodiorite compositions (IUGS terminology) form the major part of the CGC. These gneisses show a range of 50-65% SiO2 and are high in Al2O3 (c. 15-19%), K2O (1.5-4%) and Sr (800-900 ppm). Most major elements show coherent, typically magmatic trends with SiO2. La and Rb show maxima at ??? 58% SiO2. Initial 87Sr/86Sr ratios are relatively high and range from 0.7052 to 0.7066. Wallrocks of the CGC are mostly metagraywacke, pelite and metavolcanic rocks at amphibolite facies; they are geochemically dissimilar to the CGC. Major and minor elements of the CGC are very similar to those of high-K orogenic, calc-alkaline andesitic suites. The CGC may have formed largely by fractionation of mantle-derived, high AlKSr basaltic liquid in an ascending diapir, having hornblende, plagioclase, and biotite as major precipitating phases. The CGC probably represents the plutonic equivalent of a continental-margin or Andean arc that formed when the Taku terrane of the Insular belt on the west collided with the previously emplaced (but also allochthonous) Stikine terrane on the east in Late Jurassic or Early Cretaceous time. ?? 1984.

  10. Habitat use and foraging patterns of molting male Long-tailed Ducks in lagoons of the central Beaufort Sea, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Reed, John; Deborah Lacroix; Richard Lanctot

    2016-01-01

    From mid-July through September, 10 000 to 30 000 Long-tailed Ducks (Clangula hyemalis) use the lagoon systems of the central Beaufort Sea for remigial molt. Little is known about their foraging behavior and patterns of habitat use during this flightless period. We used radio transmitters to track male Long-tailed Ducks through the molt period from 2000 to 2002 in three lagoons: one adjacent to industrial oil field development and activity and two in areas without industrial activity. We found that an index to time spent foraging generally increased through the molt period. Foraging, habitat use, and home range size showed similar patterns, but those patterns were highly variable among lagoons and across years. Even with continuous daylight during the study period, birds tended to use offshore areas during the day for feeding and roosted in protected nearshore waters at night. We suspect that variability in behaviors associated with foraging, habitat use, and home range size are likely influenced by availability of invertebrate prey. Proximity to oil field activity did not appear to affect foraging behaviors of molting Long-tailed Ducks.

  11. Concentrations of Selected Pharmaceuticals and Antibiotics in South-Central Pennsylvania Waters, March through September 2006

    USGS Publications Warehouse

    Loper, Connie A.; Crawford, J. Kent; Otto, Kim L.; Manning, Rhonda L.; Meyer, Michael T.; Furlong, Edward T.

    2007-01-01

    This report presents environmental and quality-control data from analyses of 15 pharmaceutical and 31 antibiotic compounds in water samples from streams and wells in south-central Pennsylvania. The analyses are part of a study by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Environmental Protection (PADEP) to define concentrations of selected emerging contaminants in streams and well water in Pennsylvania. Sampling was conducted at 11 stream sites and at 6 wells in 9 counties of south-central Pennsylvania. Five of the streams received municipal wastewater and 6 of the streams received runoff from agricultural areas dominated by animal-feeding operations. For all 11 streams, samples were collected at locations upstream and downstream of the municipal effluents or animal-feeding operations. All six wells were in agricultural settings. A total of 120 environmental samples and 21 quality-control samples were analyzed for the study. Samples were collected at each site in March/April, May, July, and September 2006 to obtain information on changes in concentration that could be related to seasonal use of compounds. For streams, 13 pharmaceuticals and 11 antibiotics were detected at least 1 time. Detections included analytical results that were estimated or above the minimum reporting limits. Seventy-eight percent of all detections were analyzed in samples collected downstream from municipal-wastewater effluents. For streams receiving wastewater effluents, the pharmaceuticals caffeine and para-xanthine (a degradation product of caffeine) had the greatest concentrations, 4.75 ug/L (micrograms per liter) and 0.853 ug/L, respectively. Other pharmaceuticals and their respective maximum concentrations were carbamazepine (0.516 ug/L) and ibuprofen (0.277 ug/L). For streams receiving wastewater effluents, the antibiotic azithromycin had the greatest concentration (1.65 ug/L), followed by sulfamethoxazole (1.34 ug/L), ofloxacin (0.329 ug

  12. Slab Geometry Control on Mantle Flow Regime: A case study from Central South America Subduction Zone

    NASA Astrophysics Data System (ADS)

    Biryol, C. B.; Beck, S. L.; Zandt, G.; Wagner, L. S.

    2013-12-01

    The subduction of oceanic lithosphere along convergent plate margins plays an important role in the dynamics of the upper mantle beneath convergent margins and major orogenic belts. Many studies of mantle dynamics show that the flow pattern of the mantle varies greatly between different subduction zones as well as within the same subduction zone. The factors that control such variations are poorly understood and need to be investigated further in order to develop a better understanding of various subduction zone processes such as the deformation of mantle beneath convergent plate margins and transport of melts and volatiles in the mantle wedge above subducting slabs. Earlier studies of mantle flow inferred from seismic anisotropy via shear-wave splitting analysis indicated that the dynamics and deformation of subducting and overriding plates as well as the slab geometry have important roles on mantle flow regime. In an effort to test the significance of these factors in constraining the mantle dynamics along the central South America subduction zone, we carried out a shear-wave splitting analysis. Our study area covers southern Peru and northwestern Bolivia encompassing the northernmost Altiplano plateau where subduction of the Nazca plate begins to gradually flatten towards the north. The major part of the data for our analysis comes from the CAUGHT temporary seismic deployment (2010 - 2012) with 49 three-component broadband seismometers. In our study we used SKS, SKKS and PKS arrivals from over 80 teleseismic earthquakes, located between the distance-range of 60 to 140 degrees. We determined polarization direction and delay-time of shear-wave arrivals that are polarized into fast and slow components and split in time. The resultant fast polarization directions indicate the direction of mantle flow beneath the study area and the delay-times show the strength and depth extend of the associated seismic anisotropy. The results of our analysis revealed a

  13. Recognition of depositional environments using programmed pyrolysis: Sparta Formation, south-central Louisiana

    SciTech Connect

    Chinn, E.W.; Lemoine, R.; Sassen, R.

    1988-09-01

    Programmed pyrolysis of mudstone provides a rapid and effective technique to recognize environments of deposition in the subsurface. Ninety-three mudstone samples from four downdip Sparta Formation wells in south-central Louisiana were analyzed using a Rock-Eval pyrolysis analyzer with total organic carbon (TOC) module. TOC and the hydrogen index were found to be the most useful parameters for distinguishing depositional environments. Detailed conventional core analysis demonstrates that the Sparta Formation in the study area represents a prograding barrier island complex consisting of reservoir quality shoreface, storm-washover, and tidal-inlet sandstone. The sandstone overlies open marine mudstone and is capped by lagoonal mudstone. Mudstone of both facies is characteristically dark brown to black, laminated, and organic rich. However, pyrolysis results reveal geochemical contrasts that can be used to distinguish between the marine mudstone facies and the lagoonal mudstone facies. Lagoonal mudstone has TOC values averaging 1.37% and hydrogen indices averaging 160. In contrast, offshore marine mudstone has much higher TOC values, which average 2.61%, and a dramatically higher average hydrogen index of 341. Average T/sub max/ of mudstone from both facies is 431/degrees/C, and S/sub 1//S/sub 2/ ratios are well below unity, showing that the Sparta Formation is thermally immature in the study area. Thermal maturity differences cannot be invoked to explain the observed geochemical differences between environments. The clear contrast of organic geochemical differences between environments. The clear contrast of organic geochemical parameters is interpreted to reflect dissimilarity in kerogen types and in modes of preservation between mudstone facies. Lagoonal mudstone contains mostly terrestrial kerogen, whereas more oil-prone marine kerogen predominates in marine mudstone.

  14. Exploring the Pacific-Australian transform plate-boundary in central South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Stern, T.; Okaya, D.; Davey, F.; Henrys, S.; Little, T.

    2006-12-01

    Lithospheric structure beneath and adjacent to the continental transform of central South Island, New Zealand (the Alpine Fault) has been investigated with both geophysical and geological methods. Principal features that have been seismically imaged include a spectacular example of a lower crustal detachment that separates the obducting greywacke-schist rocks from lower crust and mantle below. This detachment can be seen as a zone of strong reflectivity that is sub-horizontal at 35 km depth beneath the Southern Alps. The detachment then forms a SE-dipping ramp that gets progressively steeper until at a depth of ~15 km it dips at 60 degrees. If the reflectivity that defines the detachment is projected upwards it would intersect with the surface trace of the Alpine Fault. In the hanging wall of the Alpine Fault low P-wave seismic wave speeds and high electrical conductivity are mapped. These properties are interpreted to mean inter-connected fluid, high fluid pressures and reduced effective normal stresses. Consistent with such high fluid pressures are extensive quartz veining and geological evidence for deep crustal embrittlement along vertical shear planes. Mantle deformation adjacent to the Alpine Fault is detected with SKS splitting results and Pn wave speeds from mutually perpendicular, offshore, seismic lines. P-wave anisotropy of up to 13% is seen in the mantle lid within 20 km of the fault. Moreover, combining SKS and Pn observations suggest that the lateral extent of mantle deformation may be as much as 200 km from the Alpine Fault, and that all the anisotropy can be assigned to finite deformation of the lithospheric mantle. Flexural modeling shows the effective elastic thickness (Te) to be vanishingly small beneath the Southern Alps. Beyond the coastlines values of Te are greater than 20 km. We propose that the weakness and the wide zone of deformation are phenomena of plate boundaries where both strike-slip and convergence have persisted for several

  15. Mid- to Late Holocene shoreline reconstruction and human occupation in Ancient Eretria (South Central Euboea, Greece)

    NASA Astrophysics Data System (ADS)

    Ghilardi, Matthieu; Psomiadis, David; Pavlopoulos, Kosmas; Çelka, Sylvie Müller; Fachard, Sylvian; Theurillat, Thierry; Verdan, Samuel; Knodell, Alex R.; Theodoropoulou, Tatiana; Bicket, Andrew; Bonneau, Amandine; Delanghe-Sabatier, Doriane

    2014-03-01

    Few studies have aimed to reconstruct landscape change in the area of Eretria (South Central Euboea, Greece) during the last 6000 years. The aim of this paper is to partially fill in this gap by examining the interaction between Mid- to Late Holocene shoreline evolution and human occupation, which is documented in the area from the Late Neolithic to the Late Roman period (with discontinuities). Evidence of shoreline displacements is derived from the study of five boreholes (maximum depth of 5.25 m below the surface) drilled in the lowlands of Eretria. Based on sedimentological analyses and micro/macrofaunal identifications, different facies have been identified in the cores and which reveal typical features of deltaic progradation with marine, lagoonal, fluvio-deltaic and fluvial environments. In addition, a chronostratigraphy has been obtained based on 20 AMS 14C radiocarbon dates performed on samples of plant remains and marine/lagoonal shells found in situ. The main sequences of landscape reconstruction in the plain of Eretria can be summarized as follows: a marine environment predominated from ca. 4000 to 3200 cal. BC and a gradual transition to shallow marine conditions is observed ca. 3200-3000 cal. BC due to the general context of deltaic progradation west of the ancient city. Subsequently, from ca. 3000 to 2000 cal. BC, a lagoon occupied the area in the vicinity of the Temple of Apollo and the settlement's development was restricted to several fluvio-deltaic levees, thus severely limiting human activities in the plain. From ca. 2000 to 800 cal. BC, a phase of shallow marine presence prevailed and constrained settlement on higher ground, forcing abandonment of the major part of the plain. Finally, since the eighth century BC, the sea has regressed southward and created the modern landscape.

  16. Structural Model of the Basement in the Central Savannah River Area, South Carolina and Georgia

    SciTech Connect

    Stephenson, D.; Stieve, A.

    1992-03-01

    Interpretation of several generations of seismic reflection data and potential field data suggests the presence of several crustal blocks within the basement beneath the Coastal Plain in the Central Savannah River Area (CSRA). The seismic reflection and refraction data include a grid of profiles that capture shallow and deep reflection events and traverse the Savannah River Site and vicinity. Potential field data includes aeromagnetic, ground magnetic surveys, reconnaissance and detailed gravity surveys. Subsurface data from recovered core are used to constrain the model.Interpretation of these data characteristically indicate a southeast dipping basement surface with some minor highs and lows suggesting an erosional pre-Cretaceous unconformity. This surface is interrupted by several basement faults, most of which offset only early Cretaceous sedimentary horizons overlying the erosional surface. The oldest fault is perhaps late Paleozoic because it is truncated at the basement/Coastal Plain interface. This fault is related in timing and mechanism to the underlying Augusta fault. The youngest faults deform Coastal Plain sediments of at least Priabonian age (40-36.6 Ma). One of these young faults is the Pen Branch faults, identified as the southeast dipping master fault for the Triassic Dunbarton basin. All the Cenozoic faults are probably related in time and mechanism to the nearby, well studied Belair fault.The study area thus contains a set of structures evolved from the Alleghanian orogeny through Mesozoic extension to Cenozoic readjustment of the crust. There is a metamorphosed crystalline terrane with several reflector/fault packages, a reactivated Triassic basin, a mafic terrane separating the Dunbarton basin from the large South Georgia basin to the southeast, and an overprint of reverse faults, some reactivated, and some newly formed.

  17. Pesticides in surface water from three agricultural basins in south-central Georgia, 1993-97

    USGS Publications Warehouse

    Hatzell, H.H.

    1996-01-01

    Twenty-two of 43 pesticides analyzed were detected in 128 water samples collected from Tucsawhatchee Creek, the Little River, and the Withlacoochee River. These streams drain agricultural basins in south-central Georgia and were sampled from March 1993 through June 1995. Herbicides were detected more frequently than insecticides. The most frequently detected herbicides were atrazineand metolachlor and the most frequently detected insecticide was carbaryl. Pesticide concentrations in the three streams were low and did not exceed U.S. Environmental Protection Agency drinking water standards. The maximum pesticide concentration was 2.6 ug/L (micrograms per liter) for propargite, a miticide detected in only one sample. The maximum concentrations of the remaining 21 pesticides were less than 0.25 ug/L. The median concentrations were equal to the method detection limit for all pesticides except atrazine (0.008 ug/L) and metolachlor (0.012 ug/L). The ratio of herbicidedetections to nondetections was largest in the planting season, smaller in the harvest season and smallest in the fallow season for the three basins.The same pattern existed for the insecticide ratios in the Little River and the Withlacoochee River. Pairwise correlations between concentrations of atrazine and metolachlor and four parameters (discharge, and concentrations of dissolved organiccarbon, suspended organic carbon, and suspended fine sediment) were evaluated for each stream. The strongest correlations existed between metolachlor and mean daily discharge and metolachlor and fine sediment in the Withlacoochee River. The only significant correlation for the Little River was between atrazine and suspended fine sediment.

  18. Land subsidence and earth fissures in south-central and southern Arizona, USA

    NASA Astrophysics Data System (ADS)

    Conway, Brian D.

    2016-05-01

    Land subsidence due to groundwater overdraft has been an ongoing problem in south-central and southern Arizona (USA) since the 1940s. The first earth fissure attributed to excessive groundwater withdrawal was discovered in the early 1950s near Picacho. In some areas of the state, groundwater-level declines of more than 150 m have resulted in extensive land subsidence and earth fissuring. Land subsidence in excess of 5.7 m has been documented in both western metropolitan Phoenix and Eloy. The Arizona Department of Water Resources (ADWR) has been monitoring land subsidence since 2002 using interferometric synthetic aperture radar (InSAR) and since 1998 using a global navigation satellite system (GNSS). The ADWR InSAR program has identified more than 25 individual land subsidence features that cover an area of more than 7,300 km2. Using InSAR data in conjunction with groundwater-level datasets, ADWR is able to monitor land subsidence areas as well as identify areas that may require additional monitoring. One area of particular concern is the Willcox groundwater basin in southeastern Arizona, which is the focus of this paper. The area is experiencing rapid groundwater declines, as much as 32.1 m during 2005-2014 (the largest land subsidence rate in Arizona State—up to 12 cm/year), and a large number of earth fissures. The declining groundwater levels in Arizona are a challenge for both future groundwater availability and mitigating land subsidence associated with these declines. ADWR's InSAR program will continue to be a critical tool for monitoring land subsidence due to excessive groundwater withdrawal.

  19. Active normal faulting along the Mt. Morrone south-western slopes (central Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Gori, Stefano; Giaccio, Biagio; Galadini, Fabrizio; Falcucci, Emanuela; Messina, Paolo; Sposato, Andrea; Dramis, Francesco

    2011-01-01

    In the present work we analyse one of the active normal faults affecting the central Apennines, i.e. the Mt. Morrone normal fault system. This tectonic structure, which comprises two parallel, NW-SE trending fault segments, is considered as potentially responsible for earthquakes of magnitude ≥ 6.5 and its last activation probably occurred during the second century AD. Structural observations performed along the fault planes have allowed to define the mainly normal kinematics of the tectonic structure, fitting an approximately N 20° trending extensional deformation. Geological and geomorphological investigations performed along the whole Mt. Morrone south-western slopes permitted us to identify the displacement of alluvial fans, attributed to Middle and Late Pleistocene by means of tephro-stratigraphic analyses and geomorphological correlations with dated lacustrine sequences, along the western fault branch. This allowed to evaluate in 0.4 ± 0.07 mm/year the slip rate of this segment. On the other hand, the lack of synchronous landforms and/or deposits that can be correlated across the eastern fault segment prevented the definition of the slip rate related to this fault branch. Nevertheless, basing on a critical review of the available literature dealing with normal fault systems evolution, we hypothesised a total slip rate of the fault system in the range of 0.4 ± 0.07 to 0.8 ± 0.09 mm/year. Moreover, basing on the length at surface of the Mt. Morrone fault system (i.e. 22-23 km) we estimated the maximum expected magnitude of an earthquake that might originate along this tectonic structure in the order of 6.6-6.7.

  20. Cancer in HIV-infected Persons from the Caribbean, Central and South America

    PubMed Central

    Fink, Valeria I.; Shepherd, Bryan E.; Cesar, Carina; Krolewiecki, Alejandro; Wehbe, Firas; Cortés, Claudia P.; Crabtree-Ramírez, Brenda; Padgett, Denis; Shafaee, Maryam; Schechter, Mauro; Gotuzzo, Eduardo; Bacon, Melanie; McGowan, Catherine; Cahn, Pedro; Masys, Daniel

    2011-01-01

    Background HIV infected individuals have heightened cancer risk. With the advent of HAART, the frequency of some AIDS defining cancers (ADC) has decreased while certain non-AIDS defining cancers (NADC) are becoming more frequent. Cancers among HIV-infected individuals in Latin American and the Caribbean have not yet been carefully studied. Methods Cancer cases among the Caribbean, Central and South American network for HIV Research (CCASAnet) cohort were identified reviewing clinical records and preexisting databases. Results There were 406 cancers reported: 331 ADC (224 Kaposi´s sarcomas and 98 non Hodgkin lymphomas). Most frequent NADC (n=75) were Hodgkin lymphoma and skin cancers. Seventy-three percent of NADC and 45% of ADC were diagnosed >1 year after HIV diagnosis. 56% of ADC occurred before HAART start. Median time from HAART start until cancer diagnosis was 2.5 years for NADC and 0.5 years for ADC (p=<0.001). Within 3372 HAART starters, 158 were diagnosed with 165 cancers (82.4% ADC); 85 cases were previous to or concomitant with HAART initiation. Incidence of cancer after HAART initiation in 8080 person-years of follow-up was 7.2 per 1000 person-years (95%CI= 5.5–9.3) for ADC and 2.7 (95%CI= 1.8–4.1) for NADC; incidence was higher in the first two months, particularly for ADC (47.6). A pre-HAART ADC was a predictor of mortality after adjusting for age, sex, and CD4 at HAART initiation. Conclusions ADC were the most frequent cancers in this region and were often diagnosed close to HIV diagnosis and HAART start. Incidence of cancer was highest around HAART initiation. PMID:21239992

  1. Groundwater chemistry and arsenic mobilization in the Holocene flood plains in south-central Bangladesh.

    PubMed

    Bhattacharya, Prosun; Hasan, M Aziz; Sracek, Ondra; Smith, Euan; Ahmed, K Matin; von Brömssen, Mattias; Huq, S M Imamul; Naidu, Ravi

    2009-04-01

    A comparative study of arsenic enrichment in the Bengal Delta (BD) was carried out in three alluvial aquifers in south-central Bangladesh. Investigated sites included Sonargaon in Narayanganj, Chandina in Comilla and Sirajdikhan in Munshiganj districts. At all sites samples from different depths were collected, and water chemistry and redox status vs. depth trends were determined. The concentrations of DOC and HCO(3)(-) were highest at Sirajdikhan site, while at the Sonargaon and Chandina sites the concentrations were lower. On the contrary, the NH(4)(+) concentration was high at the Chandina site as compared to the other sites. There was a good match between dissolved As and Fe at the Sirajdikhan and Sonargaon sites, but not at the Chandina site. The dissolved aqueous concentration of Mn was low at the Chandina site, which suggested that the Mn(IV) redox buffering step was missing. Speciation modeling indicated a possibility of siderite precipitation at all sites, but precipitation of rhodochrosite only at the Sonargaon and Sirajdikhan sites. At the Sirajdikhan site, the log P(CO2) values were very high (-1.37), which revealed the production of CO(2) in redox processes. Principal component analysis (PCA) indicated an impact of sea water and redox status of different samples. These results suggest that the dissolved As is de-coupled from dissolved Mn because when released, As is re-adsorbed onto the Fe(III) minerals in solid phase, as well as from dissolved Fe when precipitation of Fe(II) minerals controls the aqueous concentrations of Fe. In addition, several other concurrent redox processes may exert kinetic constraints depending on refractory characteristics of Fe(III) minerals. PMID:19125338

  2. Risk across disciplines: An interdisciplinary examination of water and drought risk in South-Central Oklahoma

    NASA Astrophysics Data System (ADS)

    Lazrus, H.; Paimazumder, D.; Towler, E.; McPherson, R. A.

    2013-12-01

    Drought is a challenge faced by communities across the United States, exacerbated by growing demands on water resources and climate variability and change. The Arbuckle-Simpson Aquifer (ASA) in south-central Oklahoma, situated in the heart of the Chickasaw Nation, is the state's only sole-source groundwater basin and sustains the Blue River, the state's only free-flowing river. The recent comprehensive hydrological studies of the aquifer indicate the need for sustainable management of the amount of water extracted. However, the question of how to deal with that management in the face of increasing drought vulnerability, diverse demands, and climate variability and change remains. Water management carries a further imperative to be inclusive of tribal and non-tribal interests. To examine this question, we are conducting an investigation of drought risk from multiple disciplines. Anthropological data comes from stakeholder interviews that were designed to investigate conflict over water management by understanding how people perceive risk differently based on different opinions about the structure of the resource, varying levels of trust in authorities, and unequal access to resources. . The Cultural Theory of Risk is used to explain how people view risks as part of their worldviews and why people who hold different worldviews disagree about risks associated with water availability. Meteorological analyses of longitudinal data indicate periods of drought that are noted in stakeholder interviews. Analysis of stream gauge data investigates the influence of climate variability on local hydrologic impacts, such as changing groundwater levels and streamflows, that are relevant to planning and management decisions in the ASA. Quantitative assessment of future drought risk and associated uncertainty and their effect on type and scale of future economic and social impacts are achieved by combining elements of statistical and dynamical downscaling to improve predictions of

  3. Population amalgamation and genetic variation: observations on artificially agglomerated tribal populations of Central and South America.

    PubMed

    Chakraborty, R; Smouse, P E; Neel, J V

    1988-11-01

    The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations of Central and South America, analyzing the pooled sample as though it were a single population. Several striking findings emerge. (1) Mean heterozygosity is not sensitive to agglomeration, but the number of different alleles (allele count) is inflated, relative to neutral mutation/drift/equilibrium expectation. (2) The inflation is most serious for rare alleles, especially those which originally occurred as tribally restricted "private" polymorphisms. (3) The degree of inflation is an increasing function of both the number of populations encompassed by the sample and of the genetic divergence among them. (4) Treating an agglomerated population as though it were a panmictic unit of long standing can lead to serious biases in estimates of mutation rates, selection pressures, and effective population sizes. Current DNA studies indicate the presence of numerous genetic variants in human populations. The findings and conclusions of this paper are all fully applicable to the study of genetic variation at the DNA level as well. PMID:3189334

  4. Origin and characteristics of discharge at San Marcos Springs, south-central Texas

    USGS Publications Warehouse

    Musgrove, MaryLynn; Crow, Cassi L.

    2013-01-01

    The Edwards aquifer in south-central Texas is one of the most productive aquifers in the Nation and is the primary source of water for the rapidly growing San Antonio area. Springs issuing from the Edwards aquifer provide habitat for several threatened and endangered species, serve as locations for recreational activities, and supply downstream users. Comal Springs and San Marcos Springs are major discharge points for the Edwards aquifer, and their discharges are used as thresholds in groundwater management strategies. Regional flow paths originating in the western part of the aquifer are generally understood to supply discharge at Comal Springs. In contrast, the hydrologic connection of San Marcos Springs with the regional Edwards aquifer flow system is less understood. During November 2008–December 2010, the U.S. Geological Survey, in cooperation with the San Antonio Water System, collected and analyzed hydrologic and geochemical data from springs, groundwater wells, and streams to gain a better understanding of the origin and characteristics of discharge at San Marcos Springs. During the study, climatic and hydrologic conditions transitioned from exceptional drought to wetter than normal. The wide range of hydrologic conditions that occurred during this study—and corresponding changes in surface-water, groundwater and spring discharge, and in physicochemical properties and geochemistry—provides insight into the origin of the water discharging from San Marcos Springs. Three orifices at San Marcos Springs (Deep, Diversion, and Weissmuller Springs) were selected to be representative of larger springs at the spring complex. Key findings include that discharge at San Marcos Springs was dominated by regional recharge sources and groundwater flow paths and that different orifices of San Marcos Springs respond differently to changes in hydrologic conditions; Deep Spring was less responsive to changes in hydrologic conditions than were Diversion Spring and

  5. Metamorphic evolution of pelitic-semipelitic granulites in the Kon Tum massif (south-central Vietnam)

    NASA Astrophysics Data System (ADS)

    Tích, Vu Van; Leyreloup, Andrey; Maluski, Henry; Lepvrier, Claude; Lo, Chinh-hua; Vượng, Nguyễn V.

    2013-09-01

    Pelitic and semipelitic anatectic granulites form one of the major lithological units in Kan Nack complex of the Kon Tum massif (in south-central Vietnam), which comprises HT metamorphic and magmatic rocks including granulites and charnockites is classically regarded as the older part of the Gondwana-derived Indosinia terrain. Metamorphic evolution study of pelitic granulite, the most abundant among granulites exposed in this massif, facilitates to understand that tectonic setting take place during the Indosinian time. The paragenetic assemblages, mineral chemistry, thermobarometry and P-T evolution path of pelitic-semipelitic granulites from Kon Tum massif has been studied in detail. Petrographic feature demonstrates that the pelitic granulite experienced prograde history, from pregranulitic conditions in the amphibolite facies up to the peak granulitic assemblages. Successive prograde reactions led to the temperature-climax giving rise to assemblages with cordierite-hercynite and cordierite-hercynite-K-feldspar. Then, as attested by the mineralogic association occurring in cordieritic coronas, these rocks have been affected by retrograde conditions coeval with a decrease of the pressure. Thermobarometic results show that the highest temperature obtained by ksp/pl thermometry is 850 °C and the highest pressure obtained by GASP (Garnet Alumino-Silicate Plagioclase) is 7.8 kbar. The obtained clockwise P-T evolution path involving heating decompression, then nearly isothermal decompression and nearly isobar cooling conditions shows that high temperature-low pressure metamorphism of the studied pelitic anatectic granulites of Kan Nack complex occurred possibly in extensional setting during the Indosinian orogeny of 260-240 Ma in age.

  6. Moisture Concentration Variation of Silages Produced on Commercial Farms in the South-Central USA

    PubMed Central

    Han, K. J.; Pitman, W. D.; Chapple, A.

    2014-01-01

    Preservation of forage crops as silage offers opportunity to avoid the high risk of rain-damaged hay in the humid south-central USA. Recent developments with baled silage or baleage make silage a less expensive option than typical chopped silage. Silage has been important in the region primarily for dairy production, but baleage has become an option for the more extensive beef cattle industry in the region. Silage samples submitted to the Louisiana State University Agricultural Center Forage Quality Lab from 2006 through 2013 were assessed for dry matter (DM) and forage nutritive characteristics of chopped silage and baleage of the different forage types from commercial farms primarily in Louisiana and Mississippi. Of the 1,308 silage samples submitted, 1,065 were annual ryegrass (AR) with small grains (SG), the warm-season annual (WA) grasses, sorghums and pearl millet, and the warm-season perennial (WP) grasses, bermudagrass and bahiagrass, providing the remaining samples. Concentration of DM was used to indicate an effective ensiling opportunity, and AR silage was more frequently within the target DM range than was the WA forage group. The AR samples also indicated a high-quality forage with average crude protein (CP) of 130 g/kg and total digestible nutrient (TDN) near 600 g/kg. The cooler winter weather at harvest apparently complicated harvest of SG silage with chopped SG silage lower in both CP and TDN (104 and 553 g/kg, respectively) than either AR silage or baleage of SG (137 and 624 g/kg for CP and TDN, respectively). The hot, humid summer weather along with large stems and large forage quantities of the WA grasses and the inherently higher fiber concentration of WP grasses at harvest stage indicate that preservation of these forage types as silage will be challenging, although successful commercial silage samples of each forage type and preservation approach were included among samples of silages produced in the region. PMID:25178295

  7. Analysis of 1995 speciated volatile organic compound data in the south central U.S.

    SciTech Connect

    Sather, M.E.; Kemp, M.G.; Yarbrough, J.W.; Kinsella, C.; Vanichchagorn, M.; Hazlett, J.

    1997-12-31

    An analysis of 1995 speciated volatile organic compound (VOC) data from three areas in the south central US has been performed for Baton Rouge, Louisiana, Houston, Texas, and El Paso, Texas. All three areas are required by the Clean Air Act Amendments of 1990 to collect ambient monitoring data for over 50 VOC species, including ten Clean Air Act Title III toxic compounds, as per the Photochemical Assessment Monitoring Stations (PAMS) requirements. The PAMS program was initiated to provide more detailed VOC data for scientists, modelers, and managers working toward eliminating violations of the ozone National Ambient Air Quality Standards (NAAQS). This paper presents useful information from a preliminary analysis of the 1995 speciated VOC and related data from Baton Rouge, Houston, and El Paso. All data analyzed were extracted from the US Environmental Protection Agency (EPA) Aerometric Information Retrieval System (AIRS) data base after collection and validation by the states of Louisiana and Texas. Key observations from the analyses include: (1) the presence of propane peaks coincident with ozone peaks during all three ozone episode days at the El Paso site; (2) the dominance of mobile source VOC emissions in the El Paso emission inventory, in contrast to the Baton Rouge and Houston VOC emission inventories, after noting strong correlations between carbon monoxide and major exhaust VOC species of gasoline; and (3) the 1995 ozone episodes at the Houston site were influenced by both morning build-up of ambient VOC concentrations and afternoon puffs of VOC emissions, while the 1995 ozone episodes at the Baton Rouge site were influenced by high early and mid-morning VOC ambient concentrations.

  8. Polycyclic aromatic hydrocarbons (PAHs) in aerosols over the central Himalayas along two south-north transects

    NASA Astrophysics Data System (ADS)

    Chen, Pengfei; Li, Chaoliu; Kang, Shichang; Rupakheti, Maheswar; Panday, Arnico K.; Zhang, Qianggong

    2016-04-01

    Our understanding of the transport of polycyclic aromatic hydrocarbons (PAHs) from the Indo-Gangetic Plains (IGP) to the Himalayas remains limited. Concentrations of PAHs were therefore measured in total suspended particles (TSP) from six sites along two south-north transects across the central Himalayas. Spatially, the annual average TSP and PAH (especially 5- and 6-ring) concentrations were found to decrease noticeably along both transects. The dry deposition fluxes had similar distribution pattern with the ambient PAH levels. Moreover, annual TSP and PAH concentrations exhibited a logarithmic decreasing pattern with increasing elevation especially in the non-monsoon seasons (TSP: y=-57.3lnx+552, R2=0.952; PAHs: y=-26.8lnx+229, R2=0.948). The TSP and PAH concentrations showed a clear seasonal variation, with the minimum concentrations around the mid-monsoon season and the maximum concentrations in winter season at Lumbini and Pokhara. While at other remote sites these pollutants were slightly higher during the non-monsoon season than those in the monsoon season. The diagnostic ratio suggested that atmospheric PAHs from the Nepal sites were mainly associated with emission of biomass, coal burning and petroleum combustion. A similar composition pattern was found between the two sides of the Himalayas, suggesting that the northern side of the Himalayas may be affected by anthropogenic emissions from the IGP due to long-range transportation as well as the unique mountain/valley breeze system which bring pollution from the IGP into Tibet across the high Himalayas.

  9. Results and interpretation of geophysical studies near the Picacho Fault, south-central Arizona

    USGS Publications Warehouse

    Pankratz, Leroy W.; Ackermann, Hans D.; Jachens, Robert C.

    1978-01-01

    Earth fissuring attributed to ground-water withdrawal occurs throughout south-central Arizona. A large zone of active fissures is located near Picacho, Arizona on the eastern rim of a large subsidence bowl. The main fissure has been named the Picacho fault. During February and March 1977, approximately 6.5 km of seismic-refraction lines were run across the Picacho fault to investigate subsurface conditions down to the crystalline basement. In addition, two lines of close-spaced gravity stations were made across the fault. The gross geologic features inferred from the gravity data agree with the seismic interpretations. Six layers were interpreted from the seismic refraction data: three layers of unconsolidated alluvium, two of denser rock of varying porosity, and the basement rock. Three significant basement faults were identified. These faults appear to lie almost directly beneath the surface fissures. Abrupt slope changes in the alluvial layers and an abrupt velocity change in the denser compacted sediments seem to be related spatially to the surface fissures. In addition there are lateral velocity differences within the basement fault blocks. In the overlying sediments a facies change in a 3.0 km/sec layer is suggested by the abrupt lateral velocity increase from 3.0 km/sec to 3.7 km/sec. This apparent facies change may in fact represent a fault plane extending upwards from the westernmost basement fault. This fault plane may even extend farther into the unconsolidated overlying sediments, inferred from basinward increases in slope, subtle basinward decreases in velocity, and a basinward elevation decrease in the top of the zone of saturation.

  10. Reconnaissance exploration geochemistry in the central Brooks Range, northern Alaska: Implications for exploration of sediment-hosted zinc-lead-silver deposits

    USGS Publications Warehouse

    Kelley, K.D.; Kelley, D.L.

    1992-01-01

    A reconnaissance geochemical survey was conducted in the southern Killik River quadrangle, central Brooks Range, northern Alaska. The Brooks Range lies within the zone of continuous permafrost which may partially inhibit chemical weathering and oxidation. The minus 30-mesh and nonmagnetic heavy-mineral concentrate fractions of sediment samples were chosen as the sample media for the survey so that mechanical rather than chemical dispersion patterns would be enhanced. A total of 263 sites were sampled within the southern half of the Killik River quadrangle at an average sample density of approximately one sample per 12 km2. All samples were submitted for multi-element analyses. In the western and central Brooks Range, several known sediment-hosted Zn-Pb-Ag(-Ba) deposits occur within a belt of Paleozoic rocks of the Endicott Mountains allochthon. Exploration for this type of deposit in the Brook Range is difficult, due to the inherently high background values for Ba, Zn and Pb in shale and the common occurrence of metamorphic quartz-calcite veins, many of which contain traces of sulfide minerals. Stream sediments derived from these sources produce numerous geochemical anomalies which are not necessarily associated with significant mineralization. R-mode factor analysis provides a means of distinguishing between element associations related to lithology and those related to possible mineralization. Factor analysis applied to the multi-element data from the southern Killik River quadrangle resulted in the discovery of two additional Zn-Pb-Ag mineral occurrences of considerable areal extent which are 80-100 km east of any previously known deposit. These have been informally named the Kady and Vidlee. Several lithogeochemical element associations, or factors, and three factors which represent sulfide mineralization were identified: Ag-Pb-Zn (galena and sphalerite) and Fe-Ni-Co-Cu (pyrite ?? chalcopyrite) in the concentrate samples and Cd-Zn-Pb-As-Mn in the sediment

  11. Flood of August 11–16, 2010, in the South Skunk River Basin, central and southeast Iowa

    USGS Publications Warehouse

    Barnes, Kimberlee K.; Eash, David A.

    2012-01-01

    Severe thunderstorm activity during August 8–11, 2010 in central and southeast Iowa resulted in major flooding from August 11–16, 2010, in the South Skunk River Basin. Rain gages at Ames and Story City recorded 96-hour rainfall amounts of 9.61 and 8.70 inches, respectively. The majority of the rainfall occurred during a 52-hour period, beginning late at night on August 8. Within the South Skunk River Basin, peak discharges of 14,800 cubic feet per second (annual flood-probability estimate of 0.2 to 1 percent) at the 05470000 South Skunk River near Ames, Iowa streamgage; of 36,200 cubic feet per second (annual flood-probability estimate of less than 0.2 percent) at the 05471000 South Skunk River below Squaw Creek near Ames, Iowa streamgage (both on August 11, 2010); and of 24,000 cubic feet per second (annual flood-probability estimate of 0.2 to 1 percent) at 05471050 South Skunk River at Colfax, Iowa streamgage on August 14 are the largest floods on record for these sites. Peak discharges at 05470500 Squaw Creek at Ames, Iowa streamgage of 22,400 cubic feet per second (annual flood-probability estimate of less than 0.2 percent) on August 11; and at 05471500 South Skunk River near Oskaloosa, Iowa streamgage, of 25,200 cubic feet per second (annual flood- probability estimate of 1 to 2 percent) on August 16 are the second highest floods on record. This report provides a description of the watershed, the thunderstorms, the flooding, and a profile of high-water marks measured at 20 locations along the South Skunk River between County Road V67/280th Avenue, northeast of Ollie in Keokuk County and West Riverside Road in Ames, a distance of 128 river miles.

  12. A river based stable isotope record of orographic precipitation: Taurus Mountains, south central Turkey

    NASA Astrophysics Data System (ADS)

    Schemmel, Fabian; Mulch, Andreas; Mikes, Tamás.; Schildgen, Taylor

    2010-05-01

    Reconstructing continental precipitation and vegetation patterns has become one of the most rapidly growing fields in terrestrial paleoclimate research. Furthermore, stable isotopes in precipitation within continental plateau regions represent an increasingly important tool for reconstructing the various effects of uplift related climate change within the world's largest plateau regions. With peak elevations of more than 3,000 m the Taurus Mountains represent the southern margin of the central Anatolian plateau and must have played a pivotal role in controlling the drainage and sedimentation patterns within the plateau interior. However, their surface uplift history remains largely elusive. We sampled a series of tributaries and rivers along the Ermenek valley that crosscuts the Taurus Mountains in Southern Turkey. The aim of this study is to quantify the modern effect of orographic rainout of the Taurus Mountains on the d18O and dD values of river and spring waters and to compare these values to the d18O and dD of recent precipitation gathered by the Global Network of Isotopes in Precipitation (GNIP). Further we try to study the trends of the recent d18O and dD isotopic composition of local rivers and precipitation in the area to create a set of isotopic data that is comparable to isotopic studies on paleosoils and can therefore be used in future paleoaltimetry and paleoclimate studies. We sampled 6 individual rivers during the fall season 2008 to capture mostly groundwater runoff in the south central Taurus Mountains. All sampled rivers belong to the same local drainage system which drains into the Mediterranean Sea. The total elevation difference within the sampling area exceeds 2,000 m and we were able to collect samples over almost 1,800 m of elevation. Our measurements show that both d18O and dD values follow the same basic trend. d18O and dD values decrease systematically with increasing elevation. The lapse rate of d18O is about -2.2 per mil/km, whereas the

  13. Peralkaline- and calc-alkaline-hosted volcanogenic massive sulfide deposits of the Bonnifield District, East-Central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Foley, Nora K.; Slack, John E.; Koenig, Alan E.; Oscarson, Robert L.

    2012-01-01

    Volcanogenic massive sulfide (VMS) Zn-Pb-Cu-Ag-Au deposits of the Bonnifield mining district formed during Late Devonian-Early Mississippian magmatism along the western edge of Laurentia. The largest deposits, Dry Creek and WTF, have a combined resource of 5.7 million tonnes at 10% Zn, 4% Pb, 0.3% Cu, 300 grams per tonne (g/t) Ag, and 1.6 g/t Au. These polymetallic deposits are hosted in high field strength element (HFSE)- and rare-earth element (REE)-rich peralkaline (pantelleritic) metarhyolite, and interlayered pyritic argillite and mudstone of the Mystic Creek Member of the Totatlanika Schist Formation. Mystic Creek metarhyolite and alkali basalt (Chute Creek Member) constitute a bimodal pair that formed in an extensional environment. A synvolcanic peralkaline quartz porphyry containing veins of fluorite, sphalerite, pyrite, and quartz intrudes the central footwall at Dry Creek. The Anderson Mountain deposit, located ~32 km to the southwest, occurs within calc-alkaline felsic to intermediate-composition metavolcanic rocks and associated graphitic argillite of the Wood River assemblage. Felsic metavolcanic rocks there have only slightly elevated HFSEs and REEs. The association of abundant graphitic and siliceous argillite with the felsic volcanic rocks together with low Cu contents in the Bonnifield deposits suggests classification as a siliciclastic-felsic type of VMS deposit. Bonnifield massive sulfides and host rocks were metamorphosed and deformed under greenschist-facies conditions in the Mesozoic. Primary depositional textures, generally uncommon, consist of framboids, framboidal aggregates, and spongy masses of pyrite. Sphalerite, the predominant base metal sulfide, encloses early pyrite framboids. Galena and chalcopyrite accompanied early pyrite formation but primarily formed late in the paragenetic sequence. Silver-rich tetrahedrite is a minor late phase at the Dry Creek deposit. Gold and Ag are present in low to moderate amounts in pyrite from all of

  14. Pliocene terrace gravels of the ancestral Yukon River near Circle, Alaska: Palynology, paleobotany, paleoenvironmental reconstruction and regional correlation

    USGS Publications Warehouse

    Ager, T.A.; Matthews, J.V., Jr.; Yeend, W.

    1994-01-01

    Gravels deposited by the ancestral Yukon River are preserved in terrace remnants on the margins of the Yukon River valley near the village of Circle in east-central Alaska. Plant fossils recovered from sandy silt lenses within these gravels include cones and needles of Picea and Larix and a variety of seeds. Seed types include several taxa which no longer grow in Alaska, such as Epipremnum, Prunus and Weigela. Pollen types recovered from these deposits represent tree and shrub taxa that grow in interior Alaska today, such as Picea, Larix, Betula and Alnus, as well as several taxa that no longer grow in interior Alaska today, such as Pinus, Tsuga, Abies and Corylus. Pollen of herb taxa identified include Gramineae, Cyperaceae, Caryophyllaceae, Compositae, Polemonium and Epilobium. The fossil flora from the gravels near Circle are similar and probably age-equivalent to the flora recovered from the Nenana Gravel in the Alaska Range 250 km to the south. Palynological and tectonic evidence summarized in this paper now suggests that the Nenana Gravel was deposited during the early and middle Pliocene. The presence of plant fossils of Tsuga, Abies, Pinus, Weigela and Prunus suggests that the mean annual temperature (MAT) of eastern interior Alaska during the early and middle Pliocene was perhaps 7-9??C warmer and less continental than today's MAT of -6.4??C. ?? 1994.

  15. Paleozoic-involving thrust array in the central Sierras Interiores (South Pyrenean Zone, Central Pyrenees): regional implications

    NASA Astrophysics Data System (ADS)

    Rodriguez, L.; Cuevas, J.; Tubía, J. M.

    2012-04-01

    This work deals with the structural evolution of the Sierras Interiores between the Tena and Aragon valleys. The Sierras Interiores is a WNW-trending mountain range that bounds the South Pyrenean Zone to the north and that is characterized by a thrust-fold system with a strong lithological control that places preferably decollements in Triassic evaporites. In the studied area of the Sierras Interiores Cenomanian limestones cover discordantly the Paleozoic rocks of the Axial Zone because there is a stratigraphic lacuna developed from Triassic to Late Cretaceous times. A simple lithostratigraphy of the study area is made up of Late Cenomanian to Early Campanian limestones with grey colour and massive aspect in landscape (170 m, Lower calcareous section), Campanian to Maastrichtian brown coloured sandstones (400-600 m, Marboré sandstones) and, finally, Paleocene light-coloured massive limestones (130-230 m), that often generate the higher topographic levels of the Sierras Interiores due to their greater resistance to erosion. Above the sedimentary sequence of the Sierras Interiores, the Jaca Basin flysch succession crops out discordantly. Based on a detailed mapping of the studied area of the Sierras Interiores, together with well and structural data of the Jaca Basin (Lanaja, 1987; Rodríguez and Cuevas, 2008) we have constructed a 12 km long NS cross section, approximately parallel to the movement direction deduced for this region (Rodríguez et al., 2011). The main structure is a thrust array made up of at least four Paleozoic-involving thrusts (the deeper thrust system) of similar thickness in a probably piggyback sequence, some of which are blind thrusts that generate fold-propagation-folds in upper levels. The higher thrust of the thrust array crops out duplicating the lower calcareous section all over the Sierras Interiores. The emplacement of the deeper thrust system generated the tightness of previous structures: south directed piggyback duplexes (the upper

  16. Molecular genotyping of Toxoplasma gondii from Central and South America revealed high diversity within and between populations.

    PubMed

    Rajendran, C; Su, C; Dubey, J P

    2012-03-01

    Recent population studies revealed that a few major clonal lineages of Toxoplasma gondii dominate in different geographical regions. The Type II and III lineages are widespread in all continents and dominate in Europe, Africa and North America. In addition, the type 12 lineage is the most common type in wildlife in North America, the Africa 1 and 3 are among the major types in Africa, and ToxoDB PCR-RFLP #9 is the major type in China. Overall the T. gondii strains are more diverse in South America than any other regions. Here, we analyzed 164 T. gondii isolates from three countries in Central America (Guatemala, Nicaragua, Costa Rica), from one country in Caribbean (Grenada) and five countries from South America (Venezuela, Colombia, Peru, Chile, and Argentina). The multilocous polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based genotyping of 11 polymorphic markers (SAG1, SAG2, alt.SAG2, SAG3, BTUB, GRA6, L358, PK1, C22-8, C29-2 and Apico) were applied to 148 free-range chicken (Gallus domesticus) isolates and 16 isolates from domestic cats (Felis catus) in Colombia; 42 genotypes were identified. Linkage disequilibrium analysis indicated more frequent genetic recombination in populations of Nicaragua and Colombia, and to a lesser degree in populations of Costa Rica and Argentina. Bayesian structural analysis identified at least three genetic clusters, and phylogenetic network analysis identified four major groups. The ToxoDB PCR-RFLP #7, Type III and II were major lineages identified from Central and South America, with high frequencies of the closely related ToxoDB PCR-RFLP #7 and Type III lineages. Taken together, this study revealed high diversity within and between T. gondii populations in Central and South America, and the dominance of Type III and its closely related ToxoDB PCR-RFLP #7 lineages. PMID:22226702

  17. Differential opening of the Central and South Atlantic Oceans and the opening of the West African rift system

    NASA Astrophysics Data System (ADS)

    Fairhead, J. D.; Binks, R. M.

    1991-02-01

    Plate tectonic studies of the development of the Central and South Atlantic Oceans using Seasat and Geosat altimeter and magnetic anomaly isochron data now provide quantitative models of seafloor spreading through time. Such models enable an initial assessment of the differential opening between these two oceanic basins to be determined. The Equatorial Atlantic is an integral part of this oceanic rifting process, allowing stresses arising from the differential opening to be dissipated into both the Caribbean and Africa along its northern and southern boundaries respectively. The tectonic model for the West African rift system, based on geological and geophysical studies, shows a series of strike-slip fault zones diverging into Africa from the Gulf of Guinea and dissipating their shear movement into the development of extensional basins orientated perpendicular to these faults zones. The development of the West African rift system was contemporaneous with the early opening of the South Atlantic, continued to develop well after the final breakup of South America from Africa and did not cease until the late Cretaceous when there was a major phase of basin inversion and deformation. Santonian ( ~ 80 Ma) deformation across the Benue Trough (Nigeria) is broadly contemporaneous with dextral shear reactivation of the central African fracture system which, in turn resulted in renewed extension in the Sudan basins during the late Cretaceous and early Tertiary. This paper illustrates the close linkage in both time and space between the history of the African rift basins and the opening of the Atlantic. Both exhibit distinct phases of evolution with the rift basins developing in direct response to the differential opening between the Central and South Atlantic in order to dissipate stresses generated by this opening. The Mesozoic tectonic model proposed is therefore one of an intimate interaction between oceanic and continental tectonics.

  18. Hydrogeologic framework of the Wood River Valley aquifer system, south-central Idaho

    USGS Publications Warehouse

    Bartolino, James R.; Adkins, Candice B.

    2012-01-01

    metamorphosed to some degree, thus rock types and their relationships vary over distance. Quaternary-age sediment and basalt compose the primary source of groundwater in the Wood River Valley aquifer system. These Quaternary deposits can be divided into three units: a coarse-grained sand and gravel unit, a fine-grained silt and clay unit, and a single basalt unit. The fine- and coarse-grained units were primarily deposited as alluvium derived from glaciation in the surrounding mountains and upper reaches of tributary canyons. The basalt unit is found in the southeastern Bellevue fan area and is composed of two flows of different ages. Most of the groundwater produced from the Wood River Valley aquifer system is from the coarse-grained deposits. The altitude of the pre-Quaternary bedrock surface in the Wood River Valley was compiled from about 1,000 well-driller reports for boreholes drilled to bedrock and about 70 Horizontal-to-Vertical Spectral Ratio (HVSR) ambient-noise measurements. The bedrock surface generally mimics the land surface by decreasing down tributary canyons and the main valley from north to south; it ranges from more than 6,700 feet in Baker Creek to less than 4,600 feet in the central Bellevue fan. Most of the south-central portion of the Bellevue fan is underlain by an apparent topographically closed area on the bedrock surface that appears to drain to the southwest towards Stanton Crossing. Quaternary sediment thickness ranges from less than a foot on main and tributary valley margins to about 350 feet in the central Bellevue fan. Hydraulic conductivity for 81 wells in the study area was estimated from well-performance tests reported on well-driller reports. Estimated hydraulic conductivity for 79 wells completed in alluvium ranges from 1,900 feet per day (ft/d) along Warm Springs Creek to less than 1 ft/d in upper Croy Canyon. A well completed in bedrock had an estimated hydraulic conductivity value of 10 ft/d, one well completed in basalt had a value of

  19. Geological Evidence of Predecessors to the 2010 Earthquake and Tsunami in South-Central Chile

    NASA Astrophysics Data System (ADS)

    Ely, L. L.; Cisternas, M.; Wesson, R. L.; Lagos, M.

    2010-12-01

    On February 27, 2010 a great M 8.8 earthquake and accompanying tsunami struck the region between Constitución and Concepción in south-central Chile. In the year immediately preceding this event, we described and surveyed deposits from previous tsunamis at several sites in the Concepción region (36.5°-38.5° S. Lat). This research positioned us to document the geomorphic and tectonic effects of the 2010 earthquake and tsunami. Following the 2010 earthquake we quantified the inundation, inland extent, erosion and deposition of the 2010 tsunami at our study sites and compared with those of previous tsunamis. The 2010 tsunami deposits were also utilized to guide the search for repositories where stratigraphic records of multiple paleotsunami deposits are likely to be preserved. The characteristic of the 2010 tsunami were similar to those reported after the penultimate earthquake in the Concepción region, which occurred in 1835. A sand sheet from the 2010 tsunami blanketed sites at Tirua (38.5° S. Lat) and the Andalien River, (36.7° S. Lat), where we had identified preexisting anomalous, laterally-continuous sand sheets that thin landward and are interbedded with coastal marsh deposits. The great similarity between these and the 2010 tsunami sands substantiated our interpretation that they were also left by previous tsunamis. At the Tirua River estuary, the 2010 tsunami sand sheet is underlain by at least three earlier tsunami deposits. This site lies at the boundary between the northern end of the rupture zone from the M 9.5 earthquake in 1960 and the southernmost reports of the 1835 and 2010 tsunamis. Prominent, laterally-continuous bands of these tsunami sands are interbedded with silty peats along the bank of the Tirua River, 0.8 to 1.8 km inland from the coast. Based on buried historic artifacts and testimonies of local survivors, the youngest pre-2010 sand sheet was deposited by the 1960 tsunami. Preliminary radiocarbon and OSL ages on the lower two sand

  20. Late Pleistocene to Holocene tephrostratigraphy of the Lonquimay Volcano, South Central Chile

    NASA Astrophysics Data System (ADS)

    Gilbert, D.; Freundt, A.; Kutterolf, S.; Burkert, C.

    2010-12-01

    The Lonquimay Volcanic Complex (LVC) in South Central Chile (38.38°S, 71.58°W) is part of the Southern Volcanic Zone of the Andes, which formed in response to the subduction of the Nazca Plate beneath the South American Plate. During the course of its magmatic evolution, the LVC produced explosive eruptions documented in the succession of widespread tephra deposits, as well as large lava flows that originated from the main edifice and several adjacent minor eruptive centers. The last eruptive phase in Lonquimays volcanic evolution occurred from 1988-1990. It led to the formation of the Navidad cinder cone with its associated 10.2 km long lava flow, and a widely distributed tephra blanket of andesitic composition (Moreno and Gardeweg, 1989). During recent field work we reinvestigated and complemented the LVC tephrostratigraphy as originally established by Polanco (1998)by detailed logging of 22 outcrops and collecting 126 stratigraphically controlled samples that were analyzed for their matrix glass, mineral and bulk rock compositions. This data set allows us to verify and extend the field-based correlations, and to establish a tephrostratigraphy for the LVC that comprises 15 stratigraphic units (LQA-LQO) and provides a framework for ongoing investigations of the petrogenetic evolution of the LVC. The stratigraphic record identifies at least 13 explosive eruptions of VEI > 3 that occurred since the last glaciation period (17150 a BP, McCulloch et al. 2000). Magmatic compositions of the tephra deposits range from basaltic scoriae (51wt% SiO2) to evolved dacitic pumice lapilli layers (67wt% SiO2), and thus have a wider compositional range than the chemically distinct andesitic lavas (57-63wt%) of the LVC. The vertical succession of tephra compositions reflects four periods of progressive magmatic differentiation, each successively tapped by several eruptions. The maximum degree of fractionation reached during these periods increases to younger ages. The

  1. Chemical quality of water in the Walnut River basin, south-central Kansas

    USGS Publications Warehouse

    Leonard, Robert B.

    1972-01-01

    Improper disposal of oil-field brine and other wastes has adversely affected the naturally diverse chemical quality of much of the water in the Walnut River basin, south-central Kansas. The basin is an area of about 2,000 square miles in the shape of a rough triangle with its apex toward the south. The Whitewater River, a principal tributary, and the Walnut River below its junction with the Whitewater River flow southward toward the Arkansas River along courses nearly coincident with the contact of the Chase and overlying Sumner Groups of Permian age. The courses of many minor tributaries are parallel to a well-developed joint system in the Permian rock. Thick interbedded limestone and shale of the Chase Group underlie the more extensive, eastern part of the basin. Natural waters are dominantly of the calcium bicarbonate type. Shale and subordinate strata of limestone, gypsum, and dolomite of the Sumner Group underlie the western part of the basin. Natural waters are dominantly of the calcium sulfate type. Inflow from most east-bank tributaries dilutes streamflow of the Walnut River; west-bank tributaries, including the Whitewater River, contribute most of the sulfate. Terrace deposits and alluvial fill along the stream channels are assigned to the Pleistocene and Holocene Series. Calcium bicarbonate waters are common as a result of the dissolution of nearly ubiquitous fragments of calcareous rock, but the chemical quality of the water in the discontinuous aquifers depends mainly on the quality of local recharge. Concentrations of dissolved solids and of one or more ions in most well waters exceeded recommended maximums for drinking water. Nearly all the ground water is hard to very hard. High concentrations of sulfate characterize waters from gypsiferous aquifers; high concentrations of chloride characterize ground waters affected by drainage from oil fields. Extensive fracture and dissolution of the Permian limestones facilitated pollution of ground water by oil

  2. North-south palaeohydrological contrasts in the central Mediterranean during the Holocene: tentative synthesis and working hypotheses

    NASA Astrophysics Data System (ADS)

    Magny, M.; Combourieu Nebout, N.; de Beaulieu, J. L.; Bout-Roumazeilles, V.; Colombaroli, D.; Desprat, S.; Francke, A.; Joannin, S.; Peyron, O.; Revel, M.; Sadori, L.; Siani, G.; Sicre, M. A.; Samartin, S.; Simonneau, A.; Tinner, W.; Vannière, B.; Wagner, B.; Zanchetta, G.; Anselmetti, F.; Brugiapaglia, E.; Chapron, E.; Debret, M.; Desmet, M.; Didier, J.; Essallami, L.; Galop, D.; Gilli, A.; Haas, J. N.; Kallel, N.; Millet, L.; Stock, A.; Turon, J. L.; Wirth, S.

    2013-04-01

    On the basis of a multi-proxy approach and a strategy combining lacustrine and marine records along a north-south transect, data collected in the Central Mediterranean within the framework of a collaborative project have led to reconstruction of high-resolution and well-dated palaeohydrological records and to assessment of their spatial and temporal coherency. Contrasting patterns of palaeohydrological changes have been evidenced in the Central Mediterranean: south (north) of around 40° N of latitude, the middle part of the Holocene was characterised by lake-level maxima (minima), during an interval dated to ca. 10 300-4500 cal BP to the south and 9000-4500 cal BP to the north. Available data suggest that these contrasting palaeohydrological patterns operated throughout the Holocene, both on millennial and centennial scales. Regarding precipitation seasonality, maximum humidity in the Central Mediterranean during the middle part of the Holocene was characterised by humid winters and dry summers north of ca. 40° N, and humid winters and summers south of ca. 40° N. This may explain an apparent conflict between palaeoclimatic records depending on the proxies used for reconstruction as well as the synchronous expansion of tree species taxa with contrasting climatic requirements. In addition, south of ca. 40° N, the first millennium of the Holocene was characterised by very dry climatic conditions not only in the Eastern, but also in the Central and the Western Mediterranean zones as reflected by low lake levels and delayed reforestation. These results suggest that, in addition to the influence of the Nile discharge reinforced by the African monsoon, the deposition of Sapropel 1 has been favoured (1) by an increase in winter precipitation in the northern Mediterranean borderlands, and (2) by an increase in winter and summer precipitation in the southern Mediterranean area. The climate reversal following the Holocene climate optimum appears to have been punctuated by

  3. Archive of digital Boomer seismic reflection data collected during USGS Cruise 94CCT02, south-central South Carolina coastal region, August 1994

    USGS Publications Warehouse

    Calderon, Karynna; Dadisman, Shawn V.; Kindinger, Jack G.; Flocks, James G.; Wiese, Dana S.

    2005-01-01

    In August of 1994, the U.S. Geological Survey, in cooperation with Coastal Carolina University, conducted marine geophysical surveys in numerous water bodies adjacent to the south-central South Carolina coastal region. Data were collected aboard the MS Coastal in the Ashley, North Edisto, Wadmalaw, Dawho, South Edisto, and Ashepoo Rivers; the Wappoo, North, Steamboat, Bohicket, and Toogoodoo Creeks; Charleston Harbor; Wadmalaw Sound; Fenwick Cut; and the Atlantic Ocean from offshore Isle of Palms to Kiawah Island. This report serves as an archive of unprocessed digital boomer seismic reflection data, trackline maps, navigation files, GIS information, observers' logbooks, Field Activity Collection System (FACS) logs, and FGDC metadata. Filtered and gained digital images of the seismic profiles are also provided. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are also provided.

  4. Effects of projected climate (2011–50) on karst hydrology and species vulnerability—Edwards aquifer, south-central Texas, and Madison aquifer, western South Dakota

    USGS Publications Warehouse

    Mahler, Barbara J.; Stamm, John F.; Poteet, Mary F.; Symstad, Amy J.; Musgrove, MaryLynn; Long, Andrew J.; Norton, Parker A.

    2014-01-01

    Karst aquifers—formed by the dissolution of soluble rocks such as limestone—are critical groundwater resources in North America, and karst springs, caves, and streams provide habitat for unique flora and fauna. Springflow and groundwater levels in karst terrane can change greatly over short time scales, and therefore are likely to respond rapidly to climate change. How might the biological communities and ecosystems associated with karst respond to climate change and accompanying changes in groundwater levels and springflow? Sites in two central U.S. regions—the Balcones Escarpment of south-central Texas and the Black Hills of western South Dakota (fig. 1)—were selected to study climate change and its potential effects on the local karst hydrology and ecosystem. The ecosystems associated with the Edwards aquifer (Balcones Escarpment region) and Madison aquifer (Black Hills region) support federally listed endangered and threatened species and numerous State-listed species of concern, including amphibians, birds, insects, and plants. Full results are provided in Stamm and others (2014), and are summarized in this fact sheet.

  5. Identification and Tracking of Polluted Air Masses in the South-Central Coast Air Basin.

    NASA Astrophysics Data System (ADS)

    Moore, G. E.; Douglas, S. G.; Kessler, R. C.; Killus, J. P.

    1991-05-01

    Canister samples of air taken during the South-Central Coast Cooperative Air Monitoring Program (SCCCAMP) 1985 field study program were analyzed for concentrations of over 50 hydrocarbons as well as chlorofluorocarbons (CFCs), carbon monoxide, hydrogen, and methane. Additional evidence of location and timing of airmass origin was obtained by utilizing long-lived halocarbons such as F-12 as `tracers of opportunity' in conjunction with known source profiles. Wind trajectories were developed from hourly gridded wind fields produced by a diagnostic wind model utilizing observed wind data. These wind trajectories were used to determine how pollutants from major source areas might be transported to sampling sites. Particulate lidar height-distance traverses were made from aircraft that provided a view of pollutant layering. Mixing height and vertical pollutant concentration distributions were obtained in order to determine if observed pollutant concentrations were consistent with the degree of stagnation present and hypothesized transport pathway.Analyses to track specific polluted air masses were conducted for the 13 September, 21 September, 23-24 September, and 2-3 October 1985 intensive study periods. The analyses find that elevated ozone concentrations during these periods are primarily attributed to transport and storage of ozone-enriched air from Los Angeles. During one type of episode (2-3 October) ozone and ozone precursors are stored near the surface over the Santa Barbara Channel overnight and transported into coastal areas on the following day. In another type of episode (23-24 September) ozone is transported into the study domain from the San Fernando Valley and Los Angeles via flow around the Santa Monica Hills. Transport of pollutant-enriched air takes place in a layer 200-500 m aloft, in many places overlaying cleaner marine-layer air. This advected ozone is mixed down to contribute to ground-level ozone concentrations over terrain where the marine layer

  6. Recharge of an Unconfined Pumice Aquifer: Winter Rainfall Versus Snow Pack, South-central Oregon

    NASA Astrophysics Data System (ADS)

    Cummings, M. L.; Weatherford, J. M.; Eibert, D.

    2015-12-01

    Walker Rim study area, an uplifted fault block east of the Cascade Range, south-central Oregon, exceeds 1580 m elevation and includes Round Meadow-Sellers Marsh closed basin, and headwaters of Upper Klamath Basin, Deschutes Basin, and Christmas Lake Valley in the Great Basin. The water-bearing unit is 2.8 to 3.0 m thick Plinian pumice fall from the Holocene eruption of Mount Mazama, Cascade Range. The perched pumice aquifer is underlain by low permeability regolith and bedrock. Disruption of the internal continuity of the Plinian pumice fall by fluvial and lacustrine processes resulted in hydrogeologic environments that include fens, wet meadows, and areas of shallow water table. Slopes are low and surface and groundwater pathways follow patterns inherited from the pre-eruption landscape. Discharge for streams and springs and depth to water table measured in open-ended piezometers slotted in the pumice aquifer have been measured between March and October, WY 2011 through WY2015. Yearly occupation on same date has been conducted for middle April, June 1st, and end of October. WY2011 and WY2012 received more precipitation than the 30 year average while WY2014 was the third driest year in 30 years of record. WY2014 and WY2015 provide an interesting contrast. Drought conditions dominated WY2014 while WY2015 was distinct in that the normal cold-season snow pack was replaced by rainfall. Cumulative precipitation exceeded the 30-year average between October and March. The pumice aquifer of wet meadows and areas of shallow water table experienced little recharge in WY2015. Persistence of widespread diffuse discharge from fens declined by middle summer as potentiometric surfaces lowered into confining peat layers or in some settings into the pumice aquifer. Recharge of the perched pumice aquifer in rain-dominated WY2015 was similar to or less than in the snow-dominated drought of WY2014. Rain falling on frozen ground drove runoff rather than aquifer recharge.

  7. Concentration and dry deposition of mercury species in arid south central New Mexico (2001-2002)

    USGS Publications Warehouse

    Caldwell, Colleen A.; Swartzendruber, Philip; Prestbo, Eric

    2006-01-01

    This research was initiated to characterize atmospheric deposition of reactive gaseous mercury (RGM), particulate mercury (HgP; <2.5 μm), and gaseous elemental mercury (Hg0) in the arid lands of south central New Mexico. Two methods were field-tested to estimate dry deposition of three mercury species. A manual speciation sampling train consisting of a KCl-coated denuder, 2.5 μm quartz fiber filters, and gold-coated quartz traps and an ion-exchange membrane (as a passive surrogate surface) were deployed concurrently over 24-h intervals for an entire year. The mean 24-h atmospheric concentration for RGM was 6.8 pg m-3 with an estimated deposition of 0.10 ng m-2h-1. The estimated deposition of mercury to the passive surrogate surface was much greater (4.0 ng m-2h-1) but demonstrated a diurnal pattern with elevated deposition from late afternoon to late evening (1400−2200; 8.0 ng m-2h-1) and lowest deposition during the night just prior to sunrise (2200−0600; 1.7 ng m-2h-1). The mean 24-h atmospheric concentrations for HgP and Hg0 were 1.52 pg m-3 and 1.59 ng m-3, respectively. Diurnal patterns were observed for RGM with atmospheric levels lowest during the night prior to sunrise (3.8 pg m-3) and greater during the afternoon and early evening (8.9 pg m-3). Discernible diurnal patterns were not observed for either HgP or Hg0. The total dry deposition of Hg was 5.9 μg m-2 year-1 with the contribution from the three species as follows:  RGM (0.88 μg m-2 year-1), HgP (0.025 μg m-2 year-1), and Hg0 (5.0 μg m-2 year-1). The annual wet deposition for total mercury throughout the same collection duration was 4.2 μg m-2 year-1, resulting in an estimated total deposition of 10.1 μg m-2 year-1 for Hg. On one sampling date, enhanced HgP (12 pg m-3) was observed due to emissions from a wildfire approximately 250 km to the east.

  8. Viability criteria for steelhead of the south-central and southern California coast

    USGS Publications Warehouse

    Boughton, David A.; Adams, Peter B.; Anderson, Eric; Fusaro, Craig; Keller, Edward A.; Kelley, Elsie; Lentsch, Leo; Nielsen, Jennifer L.; Perry, Katie; Regan, Helen; Smith, Jerry; Swift, Camm C.; Thompson, Lisa; Watson, Fred

    2007-01-01

    Recovery planning for threatened and endangered steelhead requires measurable, objective criteria for determining an acceptably low risk of extinction. Here we propose viability criteria for two levels of biological organization: individual populations, and groups of populations within the SouthCentral/Southern California Coast Steelhead Recovery Planning Domain. For populations, we adapt criteria commonly used by the IUCN (The World Conservation Union) for identifying at-risk species. For groups of populations we implement a diversity-based “representation and redundancy rule,” in which diversity includes both life-history diversity and biogeographic groupings of populations. The resulting criteria have the potential for straightforward assessment of the risks posed by evolutionary, demographic, environmental, and catastrophic factors; and are designed to use data that are readily collected. However, our prescriptive approach led to one criterion whose threshold could not yet be specified due to inadequate data, and others in which the simplicity of the criteria may render them inefficient for populations with stable run sizes or stable life-history polymorphisms. Both of these problems could likely be solved by directed programs of research and monitoring aimed at developing more efficient (but equally risk-averse) “performance-based criteria.” Of particular utility would be data on the natural fluctuations of populations, research into the stabilizing influence of life-history polymorphisms, and research on the implications of drought, wildfires, and fluvial sediment regimes. Research on estuarine habitat could also yield useful information on the generality and reliability of its role as nursery habitat. Currently, risk assessment at the population level is not possible due to data deficiency, highlighting the need to implement a comprehensive effort to monitor run sizes, anadromous fractions, spawner densities and perhaps marine survival. Assessment at

  9. Measuring and computing natural ground-water recharge at sites in south-central Kansas

    USGS Publications Warehouse

    Sophocleous, M.A.; Perry, C.A.

    1987-01-01

    To measure the natural groundwater recharge process, two sites in south-central Kansas were instrumented with sensors and data microloggers. The atmospheric-boundary layer and the unsaturated and saturated soil zones were monitored as a single regime. Direct observations also were used to evaluate the measurements. Atmospheric sensors included an anemometer, a tipping-bucket rain gage, an air-temperature thermistor, a relative-humidity probe, a net radiometer, and a barometric-pressure transducer. Sensors in the unsaturated zone consisted of soil-temperature thermocouples, tensiometers coupled with pressure transducers and dial gages, gypsum blocks, and a neutron-moisture probe. The saturated-zone sensors consisted of a water-level pressure transducer, a conventional float gage connected to a variable potentiometer, soil thermocouples, and a number of multiple-depth piezometers. Evaluation of the operation of these sensors and recorders indicates that certain types of equipment, such as pressure transducers, are very sensitive to environmental conditions. A number of suggestions aimed at improving instrumentation of recharge investigations are outlined. Precipitation and evapotranspiration data, taken together with soil moisture profiles and storage changes, water fluxes in the unsaturated zone and hydraulic gradients in the saturated zone at various depths, soil temperature, water table hydrographs, and water level changes in nearby wells, describe the recharge process. Although the two instrumented sites are located in sand-dune environments in area characterized by a shallow water table and a sub-humid continental climate, a significant difference was observed in the estimated total recharge. The estimates ranged from less than 2.5 mm at the Zenith site to approximately 154 mm at the Burrton site from February to June 1983. The principal reasons that the Burrton site had more recharge than the Zenith site were more precipitation, less evapotranspiration, and a

  10. Aeromagnetic interpretation in the south-central Zimbabwe Craton: (reappraisal of) crustal structure and tectonic implications

    NASA Astrophysics Data System (ADS)

    Ranganai, Rubeni T.; Whaler, Kathryn A.; Ebinger, Cynthia J.

    2015-12-01

    Regional aeromagnetic data from the south-central Zimbabwe Craton have been digitally processed and enhanced for geological and structural mapping and tectonic interpretation integrated with gravity data, to constrain previous interpretations based on tentative geologic maps and provide new information to link these structural features to known tectonic events. The derived maps show excellent correlation between magnetic anomalies and the known geology, and extend lithological and structural mapping to the shallow/near subsurface. In particular, they reveal the presence of discrete crustal domains and several previously unrecognised dykes, faults, and ultramafic intrusions, as well as extensions to others. Five regional structural directions (ENE, NNE, NNW, NW, and WNW) are identified and associated with trends of geological units and cross-cutting structures. The magnetic lineament patterns cut across the >2.7 Ga greenstone belts, which are shown by gravity data to be restricted to the uppermost 10 km of the crust. Therefore, the greenstone belts were an integral part of the lithosphere before much of the upper crustal (brittle) deformation occurred. Significantly, the observed magnetic trends have representatives craton-wide, implying that our interpretation and inferences can be applied to the rest of the craton with confidence. Geological-tectonic correlation suggests that the interpreted regional trends are mainly 2.5 Ga (Great Dyke age) and younger, and relate to tectonic events including the reactivation of the Limpopo Belt at 2.0 Ga and the major regional igneous/dyking events at 1.8-2.0 Ga (Mashonaland), 1.1 Ga (Umkondo), and 180 Ma (Karoo). Thus, their origin is here inferred to be inter- and intra-cratonic collisions and block movements involving the Zimbabwe and Kaapvaal Cratons and the Limpopo Belt, and later lithospheric heating and extension associated with the break-up of Gondwana. The movements produced structures, or reactivated older fractures

  11. Channel adjustments to historical disturbances along the lower Brazos and Sabine Rivers, south-central USA

    NASA Astrophysics Data System (ADS)

    Heitmuller, Franklin T.

    2014-01-01

    Historical channel adjustments are documented and discussed in context with anthropogenic disturbances along two meandering, coastal plain rivers - the lower Brazos and Sabine Rivers in the south-central United States. Hard-copy streamflow-measurement notes of the U.S. Geological Survey were utilized to render historical cross sections (1925-2007) at nine gauging stations, which were complemented with repeat photographs and flood-frequency analysis to assess trajectories of channel change and interpret causative mechanisms. Downstream- and upstream-propagating disturbances caused episodes of channel-bed incision and aggradation at different locations for distinct time periods along both rivers. Incision associated with upstream dams is detected, but channels are compensated downstream with sediment inputs from lateral channel migration and tributaries. In one case, temporary aggradation along the Brazos River at Waco was likely caused by a combination of dam construction and regional soil erosion. Channel-bed incision on the lowermost Brazos River is unrelated to dams, but is associated with instream aggregate extraction, possibly in conjunction with downstream channelization. On the Sabine River, extensive aggradation during the 1930s might be associated with logging activities (1880s-1930s), but whether the cause is pervasive regional-scale hillslope erosion or local-scale mill-site activities is indeterminate. Following passage of this sediment, the river generally recovered to pre-disturbance conditions and has exhibited stability despite a mainstem reservoir. Translation of this sediment slug is attenuated by a transition to a flood-prone, distributary-dominated system downstream of the Holocene-Pleistocene terrace onlap position. Additional findings include cross-channel hingepoints separating thalweg incision from simultaneous point-bar or bank accretion at meander bends, which indicates channel adjustment occurs along non-cohesive beds in preference to

  12. Sedimentary imprints of tsunami and storm deposits on the Shizuoka coastline, south central Japan

    NASA Astrophysics Data System (ADS)

    Garrett, Ed; Heyvaert, Vanessa M. A.; Fujiwara, Osamu; Brückner, Helmut; Yokoyama, Yusuke; Riedesel, Svenja; Miyairi, Yosuke; Shishikura, Masanobu; De Batist, Marc

    2016-04-01

    Differentiating between the deposits left by extreme wave events - including tsunamis and storms - presents a major challenge for the palaeotsunami and palaeotempestology communities. The coast of Shizuoka Prefecture, south central Japan, is impacted by typhoons and by tsunamis triggered by great subduction zone earthquakes along the adjacent Nankai Trough. A low-lying organic swale close to the town of Shirasuka is well-placed to preserve sedimentary layers left by both event types. The swale lies between a 5 to 10 metre high beach ridge and a 60 to 80 m high riser of the mid-Pleistocene Tenpakubara marine terrace. Investigating the stratigraphy and sedimentology of the site, Komatsubara et al. (2008) identified seven sand layers and attributed these to four tsunamis and one storm, with two sand layers identified as of terrestrial origin. Revisiting the site, we adopted a multi-proxy approach to further analyse the characteristics of selected deposits. We visualise the stratigraphy of retrieved vibrocores in 2D with linescan photography and in 3D with X-ray computed tomography. While problems remain in attempting to fully correlate all sedimentary layers with the published stratigraphy, we suggest that this reflects the difficulties of using a vibrocoring system in an environment characterised by alternating units of unconsolidated sand and compressible humic mud. Nevertheless, by focussing on sand units that are entirely contained within single core sections and by applying Bayesian age models based on new radiocarbon dates, we are able to identify and correlate selected sand layers. Radiocarbon ages, derived from terrestrial plant macrofossils and the acid-insoluble organic fraction of bulk samples sieved to <180 μm, constrain the timing of sand sheet emplacement, facilitating correlation with the historical record. We combine X-ray diffraction, geophysical characterisation and particle size analysis to provide a comprehensive assessment of the variations

  13. Comparative Study Of Focal Mechanisms In South Central Chile Before And After The 2010 Maule Earthquake

    NASA Astrophysics Data System (ADS)

    Agurto, H.; Rietbrock, A.; Ryder, I. M.; Haberland, C. A.

    2011-12-01

    On 27 February 2010, a Mw=8.8 earthquake occurred off the coast of south central Chile rupturing nearly 500 km of the subduction zone plate interface. The earthquake also generated a tsunami and caused more than 500 fatalities. The largest earthquakes recorded have taken place along subduction margins (e.g. Chile 1960, 2010, Andaman-Sumatra 2004, Japan 2011) and understanding their rupture mechanisms and deformation regimes is therefore of vital importance. From November 2004 to October 2005, the TIPTEQ project ("From The Incoming Plate to megaThrust EarthQuake"; Rietbrock et al., 2007; Haberland et al., 2009) maintained a network of 120 seismic stations inland and 10 stations at sea between 37 and 39° lat. S., continuously-recording and monitoring the seismicity occurring in the area before the 2010 Maule earthquake. By using first motion polarities and moment tensor inversion we have computed and analyzed focal mechanisms for a subset of data from these records. We found thrust faulting along the subduction interface down to a depth of ~30 km, followed by a gap in the seismicity and then deeper earthquakes showing diverse faulting mechanisms more sparsely distributed within the subducting plate. We also see strike-slip crustal faulting occurring down to ~12 km depth within the area of the Lanalhue fault. The most striking observation is the presence of deep (40 km) normal faulting seismicity in the fore-arc, close to the trench. We have now started to analyze the International Maule Aftershocks Dataset (IMAD) of the 2010 earthquake in the southern rupture region. Again we observe thrust faulting in the subduction interface and a seismic gap between an upper and lower zone of seismicity along the interface. By comparison of the pre- and post-earthquake datasets we are investigating whether the Maule earthquake caused any changes in the style of deformation in this part of Chile. References Haberland, C., A. Rietbrock, D. Lange, K. Bataille, and T. Dahm (2009

  14. Elastic expansion of the lithosphere caused by groundwater withdrawal in south-central Arizona

    USGS Publications Warehouse

    Holzer, T.L.

    1979-01-01

    Relative crustal uplift observed from 1948-1949 to 1967 in the Lower Santa Cruz River Basin in south-central Arizona is attributed at least in part to elastic expansion of the lithosphere induced by the removal, and subsequent loss by evapo transpiration, of 4.35 ?? 1013 kg of groundwater from alluvium. The area of unloading is approximately 8070 km2. Uplift, relative to an apparently stable area west of the unloaded area, was observed in two areas near Casa Grande and Florence where crystalline bedrock is either close to the land surface or crops out through alluvium from which groundwater was withdrawn. The magnitudes of uplift were approximately 6.3 and 7.5 cm respectively. The observations are based on first-order leveling. The observations are significant at three standard deviations for random surveying errors, and are not believed to be affected by systematic errors. However, the 7.5-cm uplift observed at Florence may be from 1 to 2 cm in excess of the actual uplift because of the possibility of subsidence of a tie point due to groundwater pumping during the leveling in 1948-1949. Uplift is attributed to groundwater withdrawal on three bases. First, the observed uplift is consistent with a theoretical evaluation of elastic expansion based on linear elasticity theory. For the observed distribution of unloading and uplift and a Poisson's ratio of 0.25, a Young's modulus for the lithosphere of approximately 0.68 Mbar is implied. This value is comparable to values of the lithosphere reported elsewhere. Second, the magnitude of uplift compares favorably with the magnitude of elastic depression caused by the formation of Lake Mead, Arizona-Nevada, 430 km northwest of the study area, when allowance is made for the different magnitudes and areal distributions of surface (un)loading. And third, in the area near Casa Grande, a reversal in the sense of bedrock displacement form subsidence of tectonic origin to uplift approximately coincided with the beginning of large

  15. Reconstructing 20th Century Summer Precipitation on the South-Central Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Conroy, J. L.; Hudson, A. M.; Overpeck, J. T.; Cole, J. E.; Liu, K.; Wang, L.

    2011-12-01

    The Tibetan Plateau has experienced significant increases in temperature over the 20th century, but trends in precipitation are less clear, as station precipitation records are sparse and satellite observations only extend back to 1979. Here we use the sediment record from Ngamring Co, a closed-basin, freshwater lake in south-central Tibet, to assess summer precipitation over the last century. Ngamring Co is located in a watershed without glaciers, so recent changes in runoff and lake level are independent of the influence of glacial ice volume. The first principal component of the Ngamring Co grain size dataset is highly correlated with median grain size and covaries significantly with local July-August precipitation from the CPC Merged Analysis of Precipitation (CMAP). From 1979 to 2007, median grain size decreases with increasing July-August precipitation and increases with decreasing July-August precipitation. There is prominent multidecadal variability in the 20th century grain size record, including a gradual decline in median grain size from 1900 to 1930, a gradual increase in median grain size from 1930 to 1990, and a rapid decline in median grain size since 1990. Median grain size values from 2000-2007 are the lowest in the 107-year record, suggesting the most abundant monsoon precipitation in the last 107 years has occurred in the last decade. Satellite images of the lake also confirm an increase in lake area since the early 1990s, but also show the greatest lake area occurred in the 1970s. Thus, although summer precipitation and lake area do covary, precipitation does not seem to control grain size by influencing lake area. We presently hypothesize that increased July-August precipitation causes enhanced erosion of the fine-grained sediment (likely paleolake sediments and loess) that blankets the slopes surrounding the lake. The ensuing runoff and deposition of this sediment into the lake then results in a decline in median grain size within the lake

  16. Meteoric fluids in the South Tibetan Detachment and palaeoaltimetry of Central Himalaya

    NASA Astrophysics Data System (ADS)

    Gébelin, Aude; Mulch, Andreas; Teyssier, Christian; Jessup, Micah J.; Brunel, Maurice; Cosca, Michael A.; Law, Rick D.

    2015-04-01

    The South Tibetan Detachment (STD) is one of the most fundamental structures within the Himalayan orogenic belt. It exposes a mylonite zone over a distance of > 1500 km along strike that is hundreds of metres thick and separates Paleozoic sedimentary units from high-grade metamorphic rocks and syntectonic leucogranites. In this study, we document the infiltration of meteoric fluids in the STD footwall at ~15 Ma when recrystallized hydrous minerals equilibrated with evolved meteoric water and therefore recorded the hydrogen isotope composition of water present during mylonitic deformation. Although these minerals deformed and recrystallized at significant depth (~10 km), they can be used as palaeoelevation proxies if they can be temporally and kinematically linked to the evolution of the STD. Stable isotope palaeoaltimetry uses the systematic relationship between the oxygen (d18O) and hydrogen (dD) isotope ratios of rainfall that scale with elevation in a predictable fashion (~2.8 per mil in d18O or ~22 per mil in dD per km). Here, we present palaeoaltimetry estimates based on the hydrogen isotope composition of synkinematic micas and amphiboles collected over 200 m of structural section from the STD into the underlying mylonitic footwall at Rongbuk Valley (Mount Everest region). Biotites reveal a very constant pattern of mid-Miocene 40Ar/39Ar plateau ages and exchanged isotopically at high temperature with D-depleted water (dDwater ~ -150 ±5 per mil) that originated from high-elevation precipitation and infiltrated the crustal hydrologic system at that time. To eliminate a climate impact on our palaeoelevation estimates, the hydrogen isotope record from the high elevation STD is compared to time-equivalent low-elevation foreland d18O records. Our palaeoaltimetry results indicate that the mean elevation of Mount Everest region during the mid-Miocene was similar to today (~5200 m). This has two main implications: (1) Strengthening of the Asian Summer Monsoon may

  17. Chemical evolution and estimated flow velocity of water in the Trinity Aquifer, south-central Texas

    USGS Publications Warehouse

    Jones, Sonya A.; Lee, Roger W.; Busby, John F.

    1997-01-01

    Three permeable zones with varying lithology and water chemistry compose the Trinity aquifer, a principal source of water in the 5,500-square-mile study area in south-central Texas. The upper permeable zone locally yields small quantities of water to wells and was not included in this study. The middle permeable zone primarily is composed of limestone with minor amounts of dolostone. Terrigenous sand and marine limestone, with minor amounts of dolostone, are the principal lithologic units in the lower permeable zone. Dissolved solids concentrations range from 329 to 1,820 milligrams per liter in water samples from the middle permeable zone and from 518 to 3,030 milligrams per liter in water samples from the lower permeable zone. Principal hydrochemical facies in the middle permeable zone are calcium magnesium bicarbonate and calcium magnesium sulfate. Hydrochemical facies in ground-water samples from the lower permeable zone vary. Tritium concentrations as large as 5.3 tritium units in the southeastern part of the study area are indicative of relatively recent recharge. Results of a geochemical mass balance simulation along a flowpath in the middle permeable zone indicate a mass transfer of 4.25 millimoles per liter of dolomite dissolved, 5.74 millimoles per liter of gypsum dissolved, 0.46 millimole per liter of sodium chloride dissolved, 8.07 millimoles per liter of calcite precipitated, and 0.67 millimole per liter of calcium-for-sodium cation exchange between solid and aqueous phases. These results support dedolomitization as a principal chemical process in the middle permeable zone of the Trinity aquifer. Results of a simulation along a flowpath in the lower permeable zone indicate a mass transfer of 0.41 millimole per liter of dolomite dissolved, 0.001 millimole per liter of gypsum dissolved, 9.58 millimoles per liter of sodium chloride dissolved, 1.09 millimoles per liter of calcite precipitated, and 1.11 millimoles per liter of sodium-for-calcium cation

  18. Palaeogeographic evolution of the central segment of the South Atlantic during Early Cretaceous times: palaeotopographic and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Chaboureau, A. C.; Guillocheau, F.; Robin, C.; Rohais, S.; Moulin, M.; Aslanian, D.

    2012-04-01

    The tectonic and sedimentary evolution of the Early Cretaceous rift of the central segment of the South Atlantic Ocean is debated. Our objective is to better constraint the timing of its evolution by drawing palaeogeographic and deformation maps. Eight palaeogeographic and deformations maps were drawn from the Berriasian to the Middle-Late Aptian, based on a biostratigraphic (ostracodes and pollens) chart recalibrated on absolute ages (chemostratigraphy, interstratified volcanics, Re-Os dating of the organic matter). The central segment of the South Atlantic is composed of two domains that have a different history in terms of deformation and palaeogeography. The southern domain includes Namibe, Santos and Campos Basins. The northern domain extends from Espirito Santo and North Kwanza Basins, in the South, to Sergipe-Alagoas and North Gabon Basins to the North. Extension started in the northern domain during Late Berriasian (Congo-Camamu Basin to Sergipe-Alagoas-North Gabon Basins) and migrated southward. At that time, the southern domain was not a subsiding domain. This is time of emplacement of the Parana-Etendeka Trapp (Late Hauterivian-Early Barremian). Extension started in this southern domain during Early Barremian. The brittle extensional period is shorter in the South (5-6 Ma, Barremian to base Aptian) than in the North (19 to 20 Myr, Upper Berriasian to Base Aptian). From Late Berriasian to base Aptian, the northern domain evolves from a deep lake with lateral highs to a shallower one, organic-rich with no more highs. The lake migrates southward in two steps, until Valanginian at the border between the northern and southern domains, until Early Barremian, North of Walvis Ridge. The Sag phase is of Middle to Late Aptian age. In the southern domain, the transition between the brittle rift and the sag phase is continuous. In the northern domain, this transition corresponds to a hiatus of Early to Middle Aptian age, possible period of mantle exhumation. Marine

  19. Holocene vegetation, fire and erosional history of City of Rocks National Reserve, South-Central Idaho

    NASA Astrophysics Data System (ADS)

    Weppner, K.; Pierce, J. L.; Betancourt, J. L.

    2011-12-01

    Climate exerts a primary control over vegetation, fire occurrence and fire-related erosion; however, vegetation is responsible for fire pattern, frequency and intensity (i.e. fire regime), as well as the nature of the fire-related erosional response (e.g. debris flows, sheet floods). Over short timescales (months to years), climate controls the availability and moisture content of vegetation as fuel. Over longer timescales (100 to 1,000 years), climate modulates the composition and structure of plant populations, which alters the associated fire regime. To explore these relationships, we compare an alluvial charcoal stratigraphy with a woodrat midden reconstruction of vegetation at City of Rocks National Reserve (CIRO), south-central Idaho. CIRO is relatively shallow-sloped terrain (mean slope ~15.6°), but bedrock knobs of erodible granite make basins responsive recorders of erosion. CIRO is dominated today by pinyon-juniper woodland, with the main species, Pinus monophylla (single-needle pinyon) and Juniperus osteosperma (Utah Juniper), occurring at their northern limits and presumed to have arrived in the late Holocene. Radiocarbon dating of 37 alluvial charcoal samples from 16 field sites in arroyos, stream terraces and alluvial fans show five episodes of enhanced fire activity. Early Holocene fires (11.7-9.5 ka) burned during shifting climate after the LGM. Mid-Holocene fires (7.2-6.7 ka) burned during a prolonged period of low lake levels (reconstructed from regional lakes and the nearby Lake Bonneville record) preceded by an extended wet period. Moderate fire activity (2.5-2 ka) corresponds to the arrival of pinyon, and follows a 2 ka period of relatively wetter conditions (~4-2 ka), indicated by regional midden records. Late Holocene fires (850-700 cal yr BP) occurred during the MCA, when regional lake levels were low and pinyon density increased. The greatest peak in fire occurred at ~550 cal yr BP during the LIA, after the establishment of pinyon as the

  20. Trace-element geochemistry of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Cooper, K.M.

    1999-01-01

    We present major- and trace- element geochemical data for 27 amphibolites and six greenstones from three structural packages in the Yukon-Tanana Upland of east-central Alaska: the Lake George assemblage (LG) of Devono-Mississippian augen gneiss, quartz-mica schist, quartzite, and amphibolite; the Taylor Mountain assemblage (TM) of mafic schist and gneiss, marble, quartzite, and metachert; and the Seventymile terrane of greenstone, serpentinized peridotite, and Mississippian to Late Triassic metasedimentary rocks. Most LG amphibolites have relatively high Nb, TiO2, Zr, and light rare earth element contents, indicative of an alkalic to tholeiitic, within-plate basalt origin. The within-plate affinities of the LG amphibolites suggest that their basaltic parent magmas developed in an extensional setting and support a correlation of these metamorphosed continental-margin rocks with less metamorphosed counterparts across the Tintina fault in the Selwyn Basin of the Canadian Cordillera. TM amphibolites have a tholeiitic or calc-alkalic composition, low normalized abundances of Nb and Ta relative to Th and La, and Ti/V values of <20, all indicative of a volcanic-arc origin. Limited results from Seventymile greenstones indicate a tholeiitic or calc-alkalic composition and intermediate to high Ti/V values (27-48), consistent with either a within-plate or an ocean-floor basalt origin. Y-La-Nb proportions in both TM and Seventymile metabasalts indicate the proximity of the arc and marginal basin to continental crust. The arc geochemistry of TM amphibolites is consistent with a model in which the TM assemblage includes arc rocks generated above a west-dipping subduction zone outboard of the North American continental margin in mid-Paleozoic through Triassic time. The ocean-floor or within-plate basalt geochemistry of the Seventymile greenstones supports the correlation of the Seventymile terrane with the Slide Mountain terrane in Canada and the hypothesis that these oceanic

  1. Lead-alpha age determinations of granitic rocks from Alaska

    USGS Publications Warehouse

    Matzko, John J.; Jaffe, H.W.; Waring, C.L.

    1957-01-01

    Lead-alpha activity age determinations were made on zircon from seven granitic rocks of central and southeastern Alaska. The results of the age determinations indicate two periods of igneous intrusion, one about 95 million years ago, during the Cretaceous period, and another about 53 million years ago, during the early part of the Tertiary. The individual ages determined on zircon from 2 rocks from southeastern Alaska and 1 from east-central Alaska gave results of 90, 100, and 96 million years; those determined on 4 rocks from central Alaska gave results of 47, 56, 58, and 51 million years.

  2. Two new crayfishes of the genus Cambarus (Decapoda: Cambaridae) from Northern Alabama and South Central Tennessee, U.S.A.

    PubMed

    Jones, Danny R; Eversole, Arnold G

    2015-01-01

    Multivariate and univariate statistical analyses of morphometric data and examination of morphological characters of the crayfish species Cambarus (Hiaticambarus) longirostris revealed the existence of two undescribed species from populations previously considered to be C. longirostris in tributaries of the Tennessee River in north Alabama and central south Tennessee. Cambarus (Hiaticambarus) andersoni and Cambarus (Hiaticambarus) diupalma differed from C. longirostris and from each other in aspects of chela morphometrics and in the presence or absence of qualitative characters. Cambarus andersoni has a corneous spine on the base of the ventral surface of the rostrum that is absent in the other two species; C. diupalma abdominal pleura are acute whereas they are subtruncate in C. andersoni and in C. longirostris. The known range of both of the new species is restricted to northern tributaries of the Tennessee River in south Tennessee and north Alabama. Cambarus diupalma is considered Endangered and C. andersoni is considered Vulnerable using American Fisheries Society conservation categorization. PMID:26701517

  3. GIS-based identification of areas with mineral resource potential for six selected deposit groups, Bureau of Land Management Central Yukon Planning Area, Alaska

    USGS Publications Warehouse

    Jones, James V., III; Karl, Susan M.; Labay, Keith A.; Shew, Nora B.; Granitto, Matthew; Hayes, Timothy S.; Mauk, Jeffrey L.; Schmidt, Jeanine M.; Todd, Erin; Wang, Bronwen; Werdon, Melanie B.; Yager, Douglas B.

    2015-01-01

    This study has used a data-driven, geographic information system (GIS)-based method for evaluating the mineral resource potential across the large region of the CYPA. This method systematically and simultaneously analyzes geoscience data from multiple geospatially referenced datasets and uses individual subwatersheds (12-digit hydrologic unit codes or HUCs) as the spatial unit of classification. The final map output indicates an estimated potential (high, medium, low) for a given mineral deposit group and indicates the certainty (high, medium, low) of that estimate for any given subwatershed (HUC). Accompanying tables describe the data layers used in each analysis, the values assigned for specific analysis parameters, and the relative weighting of each data layer that contributes to the estimated potential and certainty determinations. Core datasets used include the U.S. Geological Survey (USGS) Alaska Geochemical Database (AGDB2), the Alaska Division of Geologic and Geophysical Surveys Web-based geochemical database, data from an anticipated USGS geologic map of Alaska, and the USGS Alaska Resource Data File. Map plates accompanying this report illustrate the mineral prospectivity for the six deposit groups across the CYPA and estimates of mineral resource potential. There are numerous areas, some of them large, rated with high potential for one or more of the selected deposit groups within the CYPA.

  4. 2011 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Maharrey, J. Zebulon; Neal, Christina A.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest at or near three separate volcanic centers in Alaska during 2011. The year was highlighted by the unrest and eruption of Cleveland Volcano in the central Aleutian Islands. AVO annual summaries no longer report on activity at Russian volcanoes.

  5. Paleogeographic evolution of the central segment of the South Atlantic during Early Cretaceous times: Paleotopographic and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Chaboureau, Anne-Claire; Guillocheau, François; Robin, Cécile; Rohais, Sébastien; Moulin, Maryline; Aslanian, Daniel

    2013-09-01

    The geodynamic processes that control the opening of the central segment of the South Atlantic Ocean (between the Walvis Ridge and the Ascension FZ) are debated. In this paper, we discuss the timing of the sedimentary and tectonic evolution of the Early Cretaceous rift by drawing eight paleogeographic and geodynamic maps from the Berriasian to the Middle-Late Aptian, based on a biostratigraphic (ostracodes and pollen) chart recalibrated on absolute ages (chemostratigraphy, interstratified volcanics, Re-Os dating of the organic matter). The central segment of the South Atlantic is composed of two domains, with a two phases evolution of the pre-drift ("rifting") times: a rift phase characterized by tilted blocks and growth strata, followed by a sag basin. The southern domain includes the Namibe, Santos and Campos Basins. The northern domain extends from the Espirito Santo and North Kwanza Basins, in the south, to the Sergipe-Alagoas and North Gabon Basins to the north. Extension started in the northern domain during the Late Berriasian (Congo-Camamu Basin to the Sergipe-Alagoas-North Gabon Basins) and migrated southward. At that time, the southern domain was not a subsiding domain (emplacement of the Parana-Etendeka Trapp). Extension started in this southern domain during the Early Barremian. The rift phase is shorter in the south (5-6 Ma, Barremian to base Aptian) than in the north (19 to 20 Myr, Upper Berriasian to base Aptian). The sag phase is of Middle to Late Aptian age. In the northern domain, this transition corresponds to a hiatus of Early to Middle Aptian age. From the Late Berriasian to base Aptian, the northern domain evolves from a deep lake with lateral highs to a shallower organic-rich one with no more highs. The lake migrates southward in two steps, until the Valanginian at the border between the northern and southern domains, until the Early Barremian, north of Walvis Ridge.

  6. Lactose intolerance genetic testing: is it useful as routine screening? Results on 1426 south-central Italy patients.

    PubMed

    Santonocito, Concetta; Scapaticci, Margherita; Guarino, Donatella; Annicchiarico, Eleonora Brigida; Lisci, Rosalia; Penitente, Romina; Gasbarrini, Antonio; Zuppi, Cecilia; Capoluongo, Ettore

    2015-01-15

    Adult-type hypolactasia is a widespread condition throughout the world, causing lactose malabsorption. Several studies suggested that the identification of C/T-13910 and G/A-22018 mutations, located upstream the gene encoding the lactase-phlorizin hydrolase (LPH), is a useful tool for the differential diagnosis of hypolactasia. We evaluated the frequencies of C/T-13910 and G/A-22018 variants in a central-south Italian population and the usefulness of lactase deficiency genetic testing in the clinic practice. The genomic DNA of 1426 patients and 1000 healthy controls from central-south Italy was isolated from peripheral whole blood and genotyped for the C/T-13910 and G/A-22018 polymorphisms by high-resolution melting analysis (HRMA) and sequencing. The frequencies of genotypes in the 1426 patients analysed were as follows: 1077 CC/GG (75.5%), 287 CT/GA (20.1%), 24 TT/AA (1.7%), 38 CC/GA (2.7%). Only 64 out of 1426 (4.5%) performed also L-BHT test, 29 of which were negative for L-BHT also in presence of different genotypes. Among the 35 individuals with L-BHT positive, 34 were CC/GG and only one CT/GA. Although lactose genetic test is a good predictor of persistence/non-persistence lactase in specific population, its use in the central-south Italy population should be limited given the high prevalence of the CCGG diplotype in normal individuals. PMID:25281930

  7. P-T-t paths and differential Alleghanian loading and uplift of the Bronson Hill terrane south central New England

    USGS Publications Warehouse

    Wintsch, R.P.; Kunk, M.J.; Boyd, J.L.; Aleinikoff, J.N.

    2003-01-01

    Late Paleozoic U-Pb ages of sphene and 40Ar/39Ar cooling ages of amphibole and muscovite from rocks of the Bronson Hill terrane in Connecticut and central Massachusetts reflect a late Paleozoic (Alleghanian) overprint on Acadian metamorphic rocks. Prograde Alleghanian sphenes crystallized during the Late Pennsylvanian, and eliminate the possibility that amphibole ages reflect delayed Permian cooling from Devonian Acadian metamorphism. Fourteen new amphibole ages from Connecticut form a north-to-south trend of decreasing age from 294 to 245 Ma, while in Massachusetts four new amphibole ages together with three others from the literature produce a random Carboniferous pattern. Seven new muscovite ages support existing data indicating uniform cooling throughout the Bronson Hill terrane through ???350??C in the Early Triassic. The rate of Permian cooling defined by amphibole-muscovite pairs increases from ???4??C/my in northern Connecticut to ???50??C/my near Long Island Sound. Hinged loading and hinged but delayed exhumation in the southern part of the Bronson Hill terrane (with the hinge in central Connecticut) explain these ages and cooling rates as well as a southerly increasing metamorphic field gradient. One-dimensional thermal modeling indicates that loading of Bronson Hill rocks must have begun by the Late Mississippian. The time of peak Alleghanian metamorphic temperature decreases southward from Early Permian in northern Connecticut to Late Permian to the south. These results demonstrate that the metamorphic effects of the Alleghanian orogeny are not restricted to the Avalon terrane of southeastern New England. On the contrary, the Alleghanian orogeny reset 40Ar/39Ar mineral ages, recrystallized minerals, partially melted felsic rocks, and transposed fabrics at least as far west as the Bronson Hill terrane in south-central New England.

  8. Hydrostratigraphic subdivisions and fault barriers of the Edwards aquifer, south-central Texas, U.S.A.

    USGS Publications Warehouse

    Maclay, R.W.; Small, T.A.

    1983-01-01

    The karstic Edwards Limestone within the Balcones Fault Zone of south-central Texas forms a productive confined aquifer that consists predominately of dense carbonate rocks and contains several layers of highly permeable and porous honeycombed rocks that have been produced by the leaching of evaporitic, tidal flat or reefal deposits. Fractures have hydraulically interconnected these layers at some places. Faults, however, commonly place rocks of very high-permeability opposite rocks of very low permeability, thus creating a lateral discontinuity and a flow barrier. At places, fault barriers probably cause partial to almost complete blockage of groundwater flow normal to the fault. ?? 1982.

  9. Description and Evaluation of Numerical Groundwater Flow Models for the Edwards Aquifer, South-Central Texas

    USGS Publications Warehouse

    Lindgren, Richard J.; Taylor, Charles J.; Houston, Natalie A.

    2009-01-01

    A substantial number of public water system wells in south-central Texas withdraw groundwater from the karstic, highly productive Edwards aquifer. However, the use of numerical groundwater flow models to aid in the delineation of contributing areas for public water system wells in the Edwards aquifer is problematic because of the complex hydrogeologic framework and the presence of conduit-dominated flow paths in the aquifer. The U.S. Geological Survey, in cooperation with the Texas Commission on Environmental Quality, evaluated six published numerical groundwater flow models (all deterministic) that have been developed for the Edwards aquifer San Antonio segment or Barton Springs segment, or both. This report describes the models developed and evaluates each with respect to accessibility and ease of use, range of conditions simulated, accuracy of simulations, agreement with dye-tracer tests, and limitations of the models. These models are (1) GWSIM model of the San Antonio segment, a FORTRAN computer-model code that pre-dates the development of MODFLOW; (2) MODFLOW conduit-flow model of San Antonio and Barton Springs segments; (3) MODFLOW diffuse-flow model of San Antonio and Barton Springs segments; (4) MODFLOW Groundwater Availability Modeling [GAM] model of the Barton Springs segment; (5) MODFLOW recalibrated GAM model of the Barton Springs segment; and (6) MODFLOW-DCM (dual conductivity model) conduit model of the Barton Springs segment. The GWSIM model code is not commercially available, is limited in its application to the San Antonio segment of the Edwards aquifer, and lacks the ability of MODFLOW to easily incorporate newly developed processes and packages to better simulate hydrologic processes. MODFLOW is a widely used and tested code for numerical modeling of groundwater flow, is well documented, and is in the public domain. These attributes make MODFLOW a preferred code with regard to accessibility and ease of use. The MODFLOW conduit-flow model

  10. Isotopic composition of water from a mine drainage site in Creede County in south central Colorado

    NASA Astrophysics Data System (ADS)

    Michel, R. L.; Williams, M. W.; Krupicka, A.; Wireman, M.; Graves, J.

    2011-12-01

    Creede County in South Central Colorado was an active area of silver mining beginning in the early 1890s. To relieve flooding in some of the mines, the Nelson Tunnel was built in the late 1890s. This tunnel still exists and acid mine drainage from the tunnel eventually flows into the Willow Creek Watershed which eventually flows into the Upper Rio Grande. The water coming out of the tunnel is high in toxic metals and the area has become part of an EPA Superfund site in an effort to find a suitable method to remediate the metal problems. Among the approaches used in the program is the use of isotopes of water and carbon to identify sources and estimate ages of the water in the drainage. Samples were collected for analysis of isotopic ratios and tritium concentrations at a series of sites within the tunnel complex from 2008-2010. In 2009 samples were also collected for analysis of isotopes in groundwater and surface water. In 2010 sampling was expanded to include four precipitation and one snow sample. Tritium concentrations in precipitation and snowfall in 2010 ranged from 3-6 tritium units with the lowest concentration found in the snow sample. The 18O isotopic ratios in precipitation for this site ranged from an average of -8.9 o/oo in summer to about -19 o/oo in winter. The six groundwater samples collected in 2009 had an average 18O isotopic concentration of -15 o/oo and tritium concentrations ranging from 7.4-9.3 TU. These results suggest that the groundwater sampled is composed largely of a mixture of summer and winter precipitation with the latter source being dominant. The tritium concentrations in groundwater exceed recent precipitation concentrations, suggesting the presence of water from the bomb-tritium transient and an age of a decade or more for the groundwater. Eight sites in the tunnel were sampled I from 2008-2010, although not all sites were sampled every year. The sampling sites included waters seeping into the tunnel as well as the outlet water

  11. Water resources in the Big Lost River Basin, south-central Idaho

    USGS Publications Warehouse

    Crosthwaite, E.G.; Thomas, C.A.; Dyer, K.L.

    1970-01-01

    The Big Lost River basin occupies about 1,400 square miles in south-central Idaho and drains to the Snake River Plain. The economy in the area is based on irrigation agriculture and stockraising. The basin is underlain by a diverse-assemblage of rocks which range, in age from Precambrian to Holocene. The assemblage is divided into five groups on the basis of their hydrologic characteristics. Carbonate rocks, noncarbonate rocks, cemented alluvial deposits, unconsolidated alluvial deposits, and basalt. The principal aquifer is unconsolidated alluvial fill that is several thousand feet thick in the main valley. The carbonate rocks are the major bedrock aquifer. They absorb a significant amount of precipitation and, in places, are very permeable as evidenced by large springs discharging from or near exposures of carbonate rocks. Only the alluvium, carbonate rock and locally the basalt yield significant amounts of water. A total of about 67,000 acres is irrigated with water diverted from the Big Lost River. The annual flow of the river is highly variable and water-supply deficiencies are common. About 1 out of every 2 years is considered a drought year. In the period 1955-68, about 175 irrigation wells were drilled to provide a supplemental water supply to land irrigated from the canal system and to irrigate an additional 8,500 acres of new land. Average. annual precipitation ranged from 8 inches on the valley floor to about 50 inches at some higher elevations during the base period 1944-68. The estimated water yield of the Big Lost River basin averaged 650 cfs (cubic feet per second) for the base period. Of this amount, 150 cfs was transpired by crops, 75 cfs left the basin as streamflow, and 425 cfs left as ground-water flow. A map of precipitation and estimated values of evapotranspiration were used to construct a water-yield map. A distinctive feature of the Big Lost River basin, is the large interchange of water from surface streams into the ground and from the

  12. Shaded Relief Mosaic of Umnak Island, Aleutian Islands, Alaska

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image is a shaded relief mosaic of Umnak Island in Alaska's Aleutian Islands.

    It was created with Airsar data that was geocoded and combined into this mosaic as part of a NASA-funded Alaska Digital Elevation Model Project at the Alaska Synthetic Aperture Radar Facility (ASF) at the University of Alaska Geophysical Institute in Fairbanks, Alaska.

    Airsar collected the Alaska data as part of its PacRim 2000 Mission, which took the instrument to French Polynesia, American and Western Samoa, Fiji, New Zealand, Australia, New Guinea, Indonesia, Malaysia, Cambodia, Philippines, Taiwan, South Korea, Japan, Northern Marianas, Guam, Palau, Hawaii and Alaska. Airsar, part of NASA's Airborne Science Program, is managed for NASA's Earth Science Enterprise by JPL. JPL is a division of the California Institute of Technology in Pasadena.

  13. Time Dependent Model of the Slow Slip Event in the Tokai Region, South Central Japan, Detected by GPS Measurements in 2001

    NASA Astrophysics Data System (ADS)

    Ohta, Y.; Kimata, F.

    2003-04-01

    The slow slip event is detected in the Tokai region, south central Japan, by national GPS network (GEONET) in 2001. Generally, as the Philippine Sea Plate is subducting toward to northwest in the Suruga-Nankai Trough, ground displacements in the direction of northwest with rates of 1-2cm/yr are detected in this area. The northwestward displacements are no longer observed at this region from the GPS measurements in 2001. Reports from the ground deformation monitoring by GSI suggest that the slow event is still advancing as of January 2003. Repeated slow slip events are estimated from the leveling and EDM ranging by Kimata et al. (2001). Mogi (1989) suggested the pre-slip of the 1944 Tonankai earthquake in the region from the leveling operated at the current day of the earthquake. Based on these past experience, we take an interest in relationship to slow slip event and plate boundary great earthquake. The 2001 Tokai slow slip models are estimated from the GPS measurements and leveling data [Ozawa et al. (2002) and Kimata et al. (2002)]. They suggest the slow slip southeastward with 10-20 cm is occurred in the area less than 100 sq km. The location of the slow slip fault is the inland of the plate boundary with low angle of subducting at a depth 20-30 km. Additionally; there are GPS stations immediately above slow slip fault, and high density. To make clear the slow slip with more detail, we are re-processing the GEONET GPS data using PPP method at GIPSY OASIS II, and discuss the time-dependent model of the slow slip event. In midterm of 2000, Tokai region came under the influence of ground deformations causes by the volcanic activity at the Miyakejima Volcano, and it makes difficult to discuss the deformation start point associated with the slow slip event from the GPS measurements. From our preliminary results, the vertical movements and shortening of base length between the neighboring GPS stations suggest that slow slip event is occurred in the western part of

  14. Evaluating Ultraviolet Radiation Exposures Determined from TOMS Satellite Data at Sites of Amphibian Declines in Central and South America

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.; Smith, David E. (Technical Monitor)

    2000-01-01

    Many amphibian species have experienced substantial population declines, or have disappeared altogether, during the last several decades at a number of amphibian census sites in Central and South America. This study addresses the use of satellite-derived trends in solar ultraviolet-B (UV-B; 280-320 nm) radiation exposures at these sites over the last two decades, and is intended to demonstrate a role for satellite observations in determining whether UV-B radiation is a contributing factor in amphibian declines. UV-B radiation levels at the Earth's surface were derived from the Total Ozone Mapping Spectrometer (TOMS) satellite data, typically acquired daily since 1979. These data were used to calculate the daily erythemal (sunburning) UV-B, or UV-B(sub ery), exposures at the latitude, longitude, and elevation of each of 20 census sites. The annually averaged UV-B(sub ery) dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels received at the Central American sites. The annually averaged UV-B(sub ery) exposures increased significantly from 1979-1998 at all 11 Central American sites examined (r(exp 2) = 0.60 - 0.79; P<=0.015), with smaller but significant increases at five of the nine South American sites (r(exp 2) = 0.24-0.42; P<=0.05). The contribution of the highest UV-B(sub ery) exposure levels (>= 6750 J/sq m*d) to the annual UV-B(sub ery) total has increased from approx. 5% to approx. 15% in Central America over the 19 year period, but actual daily exposures for each species are unknown. Synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats is discussed. These findings justify further research concerning whether UV-B(sub ery) radiation plays a role in amphibian population declines and extinctions.

  15. Deformation of quaternary strata and its relationship to crustal folds and faults, south-central Puget Lowland, Washington State

    USGS Publications Warehouse

    Booth, D.B.; Troost, K.G.; Hagstrum, J.T.

    2004-01-01

    Folded Quaternary deposits across the south-central Puget Lowland, an area just south of the Seattle fault that extends across the Seattle uplift and its boundary with the adjacent Tacoma basin, provide increased resolution of the character and rate of crustal deformation. They also constrain alternative, and partly incompatible, views of crustal structure previously suggested by geophysical investigations. Tectonic deformation has been progressive for at least the past few hundred thousand years: older sediments display greater deformation than the youngest exposed deposits in the study area. Strain rates across the Seattle uplift have probably been between 0.25 and 1.0 mm/yr during this period, accounting for ???10% of the total strain shortening of the western Washington crust. The Seattle uplift displays Quaternary deformation across its full north-south extent and has structural discontinuities at both its northern and southern boundaries. Previous workers have already established the faulted nature of its northern boundary; exposed Quaternary strata across its southern boundary display intense folding, the location of which generally corresponds to the projection of a "Tacoma fault" suggested by prior geophysical studies. ?? 2004 Geological Society of America.

  16. Flood-Inundation Maps of Selected Areas Affected by the Flood of October 2015 in Central and Coastal South Carolina

    USGS Publications Warehouse

    Musser, Jonathan W.; Watson, Kara M.; Painter, Jaime A.; Gotvald, Anthony J.

    2016-01-01

    Heavy rainfall occurred across South Carolina during October 1–5, 2015, as a result of an upper atmospheric low-pressure system that funneled tropical moisture from Hurricane Joaquin into the State. The storm caused major flooding in the central and coastal parts of South Carolina. Almost 27 inches of rain fell near Mount Pleasant in Charleston County during this perio